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Channel Catfish (channel + catfish)
Kinds of Channel Catfish Terms modified by Channel Catfish Selected AbstractsGrowth and Survival of Channel Catfish, Ictalurus punctatus, Fry Fed Diets with 36 or 45% Total Protein and All Plant or Animal Protein SourcesJOURNAL OF THE WORLD AQUACULTURE SOCIETY, Issue 1 2010Todd D. Sink The basic nutrient requirements for channel catfish, Ictalurus punctatus, are well known, with anecdotal evidence suggesting that catfish fry grow faster and have better survival when fed an animal protein diet. However, the ability to grow channel catfish as small as 11 g on all plant diets and a lack of published data showing the superiority of fish or animal proteins compared to nutritionally equivalent plant proteins for catfish fry indicates that it may be possible to raise channel catfish fry on diets with only plant protein sources. Therefore, an experiment was conducted to compare the effects of 36 and 45% animal protein diets and 36 and 45% all plant protein diets on catfish fry growth and survival. Experimental diets were formulated to contain: 36% all plant protein (primarily from soybean meal); 36% animal and plant protein (,45% of crude protein as fish meal); 45% all plant protein (primarily from soy protein concentrate and soybean meal); and 45% animal and plant protein (,60% of crude protein as fish meal). The catfish were fed at a rate of 20% of body weight daily for 28 d using 24-h automated feeders. Mean ending weights and lengths of catfish fry were not significantly different (P > 0.05) for any treatment. Mean mortality was also not significantly different (P > 0.05) among diets. Regression analysis of growth rate and analysis of variance of final weights revealed that there was no significant difference in growth rate for any of the four diets. These results indicate that growth is not limited in channel catfish fry fed all plant protein diets, and that there is no apparent advantage to the inclusion of animal protein in diets for channel catfish fry. [source] Evaluation of Glycerol from Biodiesel Production as a Feed Ingredient for Channel Catfish, Ictalurus punctatusJOURNAL OF THE WORLD AQUACULTURE SOCIETY, Issue 1 2010Menghe H. Li Glycerol is the main by-product of biodiesel production from vegetable oils and animal fats. It has been evaluated as an energy source for several farm animals. A study was conducted to examine the effects of various levels of glycerol in channel catfish, Ictalurus punctatus, diets. Fish with mean initial weight of 6.8 ± 0.1 g were stocked in 110-L flow-through aquaria and fed practical diets containing 0, 5, 10, 15, and 20% glycerol for 9 wk. There were no significant differences in feed consumption, weight gain, feed efficiency ratio, and liver lipid level among fish fed diets containing 0, 5, and 10% glycerol. However, fish fed diets containing 15 and 20% glycerol had reduced weight gain, feed efficiency, and liver lipid content. Survival was not affected by dietary glycerol levels. Blood glucose level was significantly higher in fish fed 5% glycerol than fish fed other diets. Fillet protein and fat generally decreased and fillet moisture increased as dietary glycerol level increased. It appears that channel catfish can utilize about 10% glycerol in the diet without adverse effects on feed consumption, weight gain, feed efficiency ratio, hemoglobin, hepatosomatic index, and liver lipid. [source] Dietary Bovine Lactoferrin Increases Resistance of Juvenile Channel Catfish, Ictalurus punctatus, to Enteric SepticemiaJOURNAL OF THE WORLD AQUACULTURE SOCIETY, Issue 2010Thomas L. Welker Juvenile channel catfish, Ictalurus punctatus, were fed nutritionally complete, practical basal diets supplemented with bovine lactoferrin (Lf) at 0, 200, 400, 800, or 1600 mg/kg diet for 5 wk. Feed intake was significantly higher in fish-fed diets supplemented with Lf compared to the control diet, but the increased feed intake did not translate to significant increases in growth performance. Hemoglobin, white and red blood cell counts, and resistance to low-water stress also were not different among dietary groups (P > 0.05). Levels of Lf in diets had a significant effect on survival of channel catfish following challenge with Edwardsiella ictaluri: catfish fed 800 or 1600 mg/kg Lf had higher survival than the groups fed the control or 200 mg Lf diet. We established the break point minimum concentration of Lf for resistance to E. ictaluri infection as 1136 mg/kg. There was not a corresponding increase in activity of nonspecific or specific immune parameters with addition of Lf to diets, but plasma iron decreased significantly in channel catfish fed bovine Lf compared to the control group. However, no clear trend for level of dietary Lf, iron status, and resistance to E. ictaluri infection could be established. [source] Effects of Varying Dietary Protein Levels and Feeding Frequencies on Condition and Reproductive Performance of Channel Catfish to Produce Hybrid CatfishJOURNAL OF THE WORLD AQUACULTURE SOCIETY, Issue 5 2009Herbert E. Quintero The interspecific hybridization of channel catfish, Ictalurus punctatus, females with blue catfish, I. furcatus, males has been identified as a method to further improve production; however, lack of spawning success has affected its commercial application. To facilitate our understanding of the interaction of brood stock nutrition and reproductive performance, we evaluated the interaction of feed quality and feeding frequency. Channel catfish females were classified into two genetic groups, namely, high and low spawning. The treatments were offered during the spring season 70,90 d prior to the start of the spawning season. Induced reproduction was performed using luteinizing hormone releasing hormone analog. Condition of the fish as well as reproductive performance using spawning success, egg production, egg size, and fertilization at 48 h were determined. Changing protein level of the diet from 32 to 42% did not influence spawning, fecundity, or fertilization, but affected egg size and biochemical composition of the eggs. Increasing the feeding frequency from three to six times per week negatively affected spawning in one of the two genetics groups, did not affect egg production and egg fertilization, but had a significant effect on egg size. Older fish performed better than younger fish in terms of spawning success and egg production. [source] Production and Processing Trait Comparisons of Channel Catfish, Blue Catfish, and Their Hybrids Grown in Earthen PondsJOURNAL OF THE WORLD AQUACULTURE SOCIETY, Issue 6 2008Mingkang Jiang Fingerling HS-5 channel catfish, Ictalurus punctatus, NWAC 103 channel catfish, D&B blue catfish, Ictalurus furcatus, HS-5 female channel × D&B male blue catfish F1 hybrids, and NWAC 103 female channel × D&B male blue catfish F1 hybrids were stocked into twenty-five 0.04-ha earthen ponds at 12,500 fish/ha and grown for 277 d. Fish were fed daily at rates from 1.0 to 3.0% biomass based on feeding activity and temperature and adjusted weekly assuming a feed conversion ratio (FCR) of 1.8 and 100% survival. At harvest, 40 fish from each pond were sampled, and all other counted and weighed. Mean survival, growth rate indexes (a), FCR, and skin-on fillet percentages were not significantly different. Mean harvest weights and net production were higher for HS-5 channel and its hybrid than for the NWAC 103 channel, NWAC 103 hybrid, and D&B blue catfish, partially because of their larger mean stocking weights. D&B blue catfish was more uniform in size than NWAC 103 channel and NWAC 103 hybrid. D&B blue catfish was the easiest to seine. HS-5 hybrids and NWAC 103 hybrids had lower mean head percentage and a better processing yield than their parent channel catfish. [source] Effects of an Extended Hatchery Phase and Vaccination against Enteric Septicemia of Catfish on the Production of Channel Catfish, Ictalurus punctatus, FingerlingsJOURNAL OF THE WORLD AQUACULTURE SOCIETY, Issue 2 2008Abel A. Carrias The present study was conducted to evaluate production management methods to improve overall survival of channel catfish, Ictalurus punctatus, fry to the fingerling stage by incorporating the use of a live, attenuated vaccine against Edwardsiella ictaluri and employing an extended hatchery phase. In this experiment, four treatments were used. In Treatment 1, 10-d posthatch (PH) fry were vaccinated and then directly stocked into earthen ponds. In Treatments 2 and 3, 10-d PH fry were sham-vaccinated (control) and vaccinated, respectively, kept in nursery tanks for 22 d, and then stocked into earthen ponds. Fry in Treatment 4 were sham-vaccinated at 10 d PH, kept in nursery tanks for 22 d, and then vaccinated prior to stocking into earthen ponds. Mean fingerling yield at harvest ranged from 4716 kg/ha in Treatment 1 to 8112 kg/ha in Treatment 4. Mean individual fish weight ranged from 38.8 g in Treatment 1 to 40.9 g in Treatment 4, and feed conversion ratios (FCR) ranged from 1.15 in Treatment 4 to 1.51 in Treatment 1. Mean survival ranged from 47.5% in Treatment 1 to 73.4% in Treatment 4. In specific comparisons to evaluate the nursery effect (Treatments 1 and 3), yield and overall survival were significantly different (P < 0.05) between these two treatments. In specific comparisons to evaluate the effect of the use of the vaccine (Treatments 2, 3, and 4), overall survival was significantly different (P < 0.05) between Treatment 2 (sham-vaccinated control with nursery phase) and Treatment 4 (vaccinated at 32 d PH with nursery phase). No significant differences (P > 0.05) in yield, average weight, and FCR were observed between treatments. Results indicate that implementing an extended hatchery phase and vaccination strategy with older fry can improve overall survival of fingerling fish. [source] Effect of Sublethal Hypoxia on the Immune Response and Susceptibility of Channel Catfish, Ictalurus punctatus, to Enteric SepticemiaJOURNAL OF THE WORLD AQUACULTURE SOCIETY, Issue 1 2007Thomas L. Welker The effect of sublethal hypoxia exposure on stress and immune responses and susceptibility to Edwardsiella ictaluri infection in juvenile channel catfish, Ictalurus punctatus, was investigated. Fish were monitored for temporal changes in glucose and cortisol concentrations before, during, and after 2 h exposure to sublethal hypoxia (<2 mg/L dissolved oxygen [DO]) and when maintained under normoxic conditions (6.0 ± 0.3 mg/L DO). Both blood glucose and plasma cortisol increased significantly in response to hypoxic conditions. Fish exposed to hypoxic or normoxic conditions were challenged with a high dose (1.3 × 107 colony-forming units [CFU]/mL) or a low dose (1.3 × 105 CFU/mL) of E. ictaluri or sterile culture broth by 30-min immersion bath. Approximately 1% of fish in both the normoxic and the hypoxic groups died when challenged with the low dose of E. ictaluri. However, when challenged with the high dose of E. ictaluri, catfish exposed to hypoxic conditions had significantly higher cumulative mortality (36 ± 12.1%) than those maintained under normoxic conditions (12 ± 1.1%). Total hemolytic complement and bactericidal activities and antibody response were lower in hypoxia-exposed channel catfish, indicating that increased susceptibility of channel catfish to E. ictaluri may be the result of the immunosuppressive effects of the stress response to hypoxia. [source] Immune Response and Resistance to Stress and Edwardsiella ictaluri Challenge in Channel Catfish, Ictalurus punctatus, Fed Diets Containing Commercial Whole-Cell Yeast or Yeast SubcomponentsJOURNAL OF THE WORLD AQUACULTURE SOCIETY, Issue 1 2007Thomas L. Welker Dietary supplementation of yeast or yeast subcomponents (YYS) as commercial preparations of ,-glucan (MacroGard®; Biotec-Mackzymal, Tromsø, Norway; and Betagard A®; Aqua-In-Tech, Inc., Seattle, WA, USA), mannan oligosaccharide (Bio-MosÔ Aqua Grade; Alltech, Nicholasville, KY, USA), or whole-cell Saccharomyces cerevisiae (Levucell SB20®; Lallemand Animal Nutrition, Milwaukee, WI, USA) at the manufacturer's recommended levels was evaluated on the physiological performance of juvenile channel catfish, Ictalurus punctatus. Fish were fed YYS diets for 4 wk, followed by 2 wk of control diet. Fish were sampled at the end of each feeding period (4 and 6 wk) to measure hematological and immune parameters and growth and to determine the effects of dietary ,-glucan on resistance to Edwardsiella ictaluri infection and to low-water stress (6 wk). Supplementation of YYS in diets did not affect growth performance, hematology, or immune function. Survival from E. ictaluri infection was from 5 to 17.5% higher in fish fed YYS diets than in the control group, but the increases were not significant. Some improvement in stress resistance was observed in YYS-fed catfish after exposure to low-water stress. Stress reduction in fish fed diets supplemented with yeast subcomponents has been reported previously, but thus far, no explanation has been proposed for this effect. The present study and the previously published research suggest that dietary YYS supplementation does not appear to improve resistance of channel catfish to E. ictaluri. [source] Effect of Multiple-batch Channel Catfish, Ictalurus punctatus, Stocking Density and Feeding Rate on Water Quality, Production Characteristics, and CostsJOURNAL OF THE WORLD AQUACULTURE SOCIETY, Issue 4 2006Brent E. Southworth To quantitatively define relationships among stocking densities, feeding rates, water quality, and production costs for channel catfish, Ictalurus punctatus, grown in multiple-batch systems, twelve 0.1-ha earthen ponds were stocked at 8,600, 17,300, 26,000, or 34,600 fingerlings/ha along with 2,268 kg/ha of carryover fish. Fish in all ponds were fed daily to apparent satiation using 32% protein floating feed. Temperature and dissolved oxygen in each pond were monitored twice daily; pH weekly; nitrite-N, total ammonia nitrogen, and Secchi disk visibility every 2 wk; nitrate-N, chlorophyll a, total nitrogen, total phosphorus, and chemical oxygen demand monthly; and chloride every other month. The costs of producing channel catfish at different stocking densities were estimated. There were no significant differences (P > 0.05) as a result of stocking density among treatment means of (1) gross or net yields, (2) mean weights at harvest, and (3) growth or survival of fingerlings (24,36%) and carryover fish (77,94%). Mean and maximum daily feeding rates ranged from 40 to 53 kg/ha/d and 123 to 188 kg/ha/d, respectively, and feed conversion ratios averaged 1.75. There were no differences in any feed-related parameter as a result of density. Water quality variables showed few differences among densities at samplings and no differences when averaged across the production season. Yield of fingerlings increased as stocking density increased with significant differences between the two highest and the two lowest stocking densities. Breakeven prices were lower at the higher stocking densities as a result of the higher yield of understocked fish and similar mean individual fish weights produced at these higher stocking densities. Overall, varying stocking densities of fingerlings in multiple-batch systems had little effect on production efficiency and water quality. Additional research on managing the population structure of carryover fish in commercial catfish ponds may be warranted. [source] Growth of Stocker Channel Catfish to Large Market Size in Single-Batch CultureJOURNAL OF THE WORLD AQUACULTURE SOCIETY, Issue 1 2004Bartholomew W. Green Catfish farmers increasingly are producing fish larger than the traditional size of 0.45-0.57 kg/fish in order to meet processing plant requirements for larger fish. Production of larger channel catfish Ictalurus punctatus in multiple-batch culture has been investigated in a few studies, but the impact of understocked fingerlings on growth of carry-over fish is unknown. The present study was conducted to quantify growth, feed conversion ratio, net daily yield, and net and total yield of stocker channel catfish grown in single-batch, one-season culture to mean individual weights of 0.60, 0.72, 0.91, or 1.17 kg/fish. Channel catfish (mean weight = 0.26 kg/fish) were stocked into 12 0.1-ha ponds at 11,115 fish/ha. Fish were fed a 32% crude protein floating extruded feed once daily to apparent satiation. When the average weight of the fish population reached the target weight, three randomly selected ponds were harvested. Fish growth was linear in all treatments. Growth rates were similar for fish grown to 0.60, 0.72, and 0.91 kg/fish, and significantly lower (P < 0.05) than for fish grown to 1.17 kg. Variation in individual fish weight increased linearly with increased duration of culture period. Feed conversion ratio averaged 1.9 and did not differ significantly among treatments. The percentage of the fish population at harvest that fell within the 0.57 to 2.04 kg-size range preferred by processing plants increased from 56.6 to 98-5% as the mean weight at harvest increased from 0.60 to 1.17 kg/fish. [source] Bioavailability of Ascorbyl-2-Monophosphate to Channel Catfish Fed Purified and Practical DietsJOURNAL OF THE WORLD AQUACULTURE SOCIETY, Issue 2 2002Wendy M. Sealey [source] Evaluation of diquat against an acute experimental infection of Flavobacterium columnare in channel catfish, Ictalurus punctatus (Rafinesque)JOURNAL OF FISH DISEASES, Issue 5 2009A M Darwish Abstract A trial was performed to evaluate the efficacy of diquat (6,7-dihydrodipyrido[1,2-a:2,,1,-c]pyrazinediium dibromide) against an acute experimental infection of Flavobacterium columnare in channel catfish, Ictalurus punctatus. Diquat is an Environmental Protection Agency-approved herbicide and has the potential to be legally and practically used against columnaris. Channel catfish were challenged, by cutaneous abrasion, and waterborne exposure to F. columnare and treated once at 22-h post-challenge with 2.5, 5.0, 10.0 and 15 mg L,1 of diquat active ingredient for 6 h. At the conclusion of the trial, 21-day post-challenge, diquat at 5.0, 10.0 and 15 mg L,1 significantly (P < 0.05) reduced the mortality of infected fish from 95% in the challenged non-treated fish to 68%, 59% and 49%, respectively. In vitro, the minimum inhibitory concentration (MIC) of 23 isolates of F. columnare was assayed. The majority of the isolates had an MIC value of 5 ,g mL,1 (15 of the 23 isolates). Infected fish exhibited acute clinical signs similar to a natural infection. The skin had severe ulcerative necrotizing dermatitis and the muscles had severe necrotizing myositis. The gills had severe multifocal necrotizing branchitis. The results demonstrate that diquat would reduce mortalities caused by an acute columnaris infection. [source] Susceptibility of channel catfish, Ictalurus punctatus (Rafinesque), to Edwardsiella ictaluri challenge following copper sulphate exposureJOURNAL OF FISH DISEASES, Issue 10 2007B R Griffin Abstract Channel catfish, Ictalurus punctatus (Rafinesque), with or without a preliminary 24 h exposure to 2 mg copper sulphate L,1, were challenged with 7.5 × 106 colony forming units L,1 of Edwardsiella ictaluri to determine the effect of copper sulphate on disease resistance. Catfish previously exposed to copper sulphate were significantly more resistant to the bacterial challenge than those not exposed. Catfish not exposed to copper sulphate suffered 35.5% mortality while catfish exposed to copper sulphate experienced 14.1% mortality. Copper concentrations were the same in tank waters of both exposed and control fish at the time of challenge, eliminating the possibility that copper in the water may have been toxic to bacteria. Copper concentrations in freeze dried and ground tissues of unexposed, exposed, and purged channel catfish were highest in fish before copper sulphate exposures suggesting that elevated tissue levels of copper were not responsible for the increased resistance to bacterial challenge. Competition for sites of bacterial attachment to gill or epithelial cells may account for the reduction in mortality; although this is not supported by the low copper content of fish tissue after copper exposure. [source] Induced cross-protection in channel catfish, Ictalurus punctatus (Rafinesque), against different immobilization serotypes of Ichthyophthirius multifiliisJOURNAL OF FISH DISEASES, Issue 3 2006D-H Xu Abstract Channel catfish, Ictalurus punctatus (Rafinesque), were immunized with Ichthyophthirius multifiliis (Ich) theronts and trophonts, and the immune response and host protection against both homologous and heterologous serotypes of Ich were evaluated. Immunizations were done with two immobilization serotypes (ARS4 and ARS6) of live theronts by bath immersion (trial I) and with sonicated trophonts by intraperitoneal (i.p.) injection (trial II). Cutaneous and serum antibody titres against Ich following immunization were measured and survival of catfish was determined after theront challenge. Theronts were immobilized by the antiserum from fish immunized with homologous theronts or trophonts, but not by the serum of fish immunized with the heterologous serotype. Serum from fish immunized by immersion with live theronts showed higher enzyme-linked immunosorbent assay titres against both homologous and heterologous serotypes than fish immunized by i.p. injection of trophonts. Channel catfish immunized by immersion with live theronts or by i.p. injection with sonicated trophonts developed an immune response against Ich and provided cross-protection against challenge from both serotypes (ARS4 and ARS6) of the parasite. Sonicated trophont antigens in aqueous solution by i.p. injection could stimulate an immune response in fish, but the immunity was of short duration. [source] Growth of Stocker Channel Catfish to Large Market Size in Single-Batch CultureJOURNAL OF THE WORLD AQUACULTURE SOCIETY, Issue 1 2004Bartholomew W. Green Catfish farmers increasingly are producing fish larger than the traditional size of 0.45-0.57 kg/fish in order to meet processing plant requirements for larger fish. Production of larger channel catfish Ictalurus punctatus in multiple-batch culture has been investigated in a few studies, but the impact of understocked fingerlings on growth of carry-over fish is unknown. The present study was conducted to quantify growth, feed conversion ratio, net daily yield, and net and total yield of stocker channel catfish grown in single-batch, one-season culture to mean individual weights of 0.60, 0.72, 0.91, or 1.17 kg/fish. Channel catfish (mean weight = 0.26 kg/fish) were stocked into 12 0.1-ha ponds at 11,115 fish/ha. Fish were fed a 32% crude protein floating extruded feed once daily to apparent satiation. When the average weight of the fish population reached the target weight, three randomly selected ponds were harvested. Fish growth was linear in all treatments. Growth rates were similar for fish grown to 0.60, 0.72, and 0.91 kg/fish, and significantly lower (P < 0.05) than for fish grown to 1.17 kg. Variation in individual fish weight increased linearly with increased duration of culture period. Feed conversion ratio averaged 1.9 and did not differ significantly among treatments. The percentage of the fish population at harvest that fell within the 0.57 to 2.04 kg-size range preferred by processing plants increased from 56.6 to 98-5% as the mean weight at harvest increased from 0.60 to 1.17 kg/fish. [source] Threadfin shad impacts phytoplankton and zooplankton community structures in channel catfish pondsAQUACULTURE RESEARCH, Issue 10 2010Bartholomew W Green Abstract Plankton community structure and chlorophyll a concentration were compared in twelve 0.1 ha earthen ponds co-stocked with channel catfish (Ictalurus punctatus Rafinesque, 1818) in a multiple-batch culture (initial biomass=5458 kg ha,1) and a planktivore, threadfin shad (Dorosoma petenense Güther, 1867; initial biomass=449 kg ha,1), during the April,November growing season. We used a completely randomized design in a 2 × 2 factorial arrangement to test the planktivore level (presence or absence of threadfin shad) and channel catfish feeding frequency (daily or every third day). Channel catfish were fed a 32% protein feed to apparent satiation on days fed. The presence of threadfin shad affected phytoplankton and zooplankton community structure more than did feeding frequency, and the impact in ponds was more pronounced after 1 July. The numbers of all major groups of zooplankton were lower in ponds with threadfin shad, but were unaffected by the feeding frequency. Chlorophyll a concentration before 1 July was higher in ponds with threadfin shad and unaffected by the feeding frequency, whereas after 1 July it was higher in ponds without threadfin shad and that were fed daily. Phytoplankton community structure after 1 July was dominated by nuisance algal bloom genera of cyanobacteria in ponds without threadfin shad and by Bacillariophyceae in ponds with threadfin shad. [source] Effect of bile salts, lipid, and humic acids on absorption of benzo[a]pyrene by isolated channel catfish (Ictalurus punctatus) intestine segmentsENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 5 2001Lynn P. Weber Abstract Dietary absorption of lipophilic contaminants may be a significant route of exposure in aquatic organisms. Bile salts, lipids, and humic acids are important factors that may influence the intestinal absorption of a contaminant such as benzo[a]pyrene (BaP). We hypothesized that bile salts, monoglycerides, and free fatty acids would increase BaP intestinal absorption, while triglycerides, humic acids, and sediment would decrease BaP intestinal absorption. We have established and validated an in vitro model to examine modification of 3H-BaP absorption in everted intestinal segments from channel catfish (Ictalurus punctatus). Uptake of BaP into the everted intestinal segments continued to increase over the times examined in this study (60 min) and apparently occurs passively; thus, fugacity-based models of uptake are supported. Absorption of BaP into intestinal cells was significantly decreased by the addition of monoglycerides and free fatty acids to bile salts in the incubation media. Addition of triglycerides decreased BaP absorption even further. Humic acids may have decreased BaP intestinal absorption, while natural sediment may have increased BaP absorption. The results of this study suggest that all lipids may decrease intestinal uptake of lipophilic contaminants if they remain in unabsorbable excess in the intestinal lumen by retaining BaP in lipid/bile micelles. In contrast, if triglycerides are hydrolyzed into monoglycerides/free fatty acids prior to absorption, lipophilic contaminant uptake will likely be facilitated. Thus, it may be the hydrolytic state of lipids that determines its effects on BaP absorption. Humic acids alone may decrease dietary uptake of BaP, but our results suggest that other components in natural sediment may counteract this effect to cause a slight enhancement of BaP uptake. Further studies are needed to determine the dietary conditions necessary for bio-accumulation to contribute significantly to lipophilic contaminant body burdens in benthivorous fish. Finally, the everted intestinal segment technique has the potential to be used in other species and with different contaminants. [source] Flavobacterium columnare chemotaxis to channel catfish mucusFEMS MICROBIOLOGY LETTERS, Issue 2 2008Phillip H. Klesius Abstract Flavobacterium columnare is a Gram-negative pathogen of many species of wild and cultured fish. Isolates from diseased channel catfish belong to either genomovar I or II. Genomovar II isolates were found to be more virulent than genomovar I isolates. The objective of the present study was to determine whether differences exist in the chemotactic response of these genomovars to mucus obtained from the skin, gills and intestines of healthy channel catfish using the capillary chemotaxis assay. Mucus from the skin and gill induced a greater chemotactic response by F. columnare than mucus from the intestine. Sixty percent of mucus from the skin of individual catfish yielded a positive chemotactic response from F. columnare. Finally, skin mucus induced a greater chemotactic response in genomovar II F. columnare than in genomovar I F. columnare isolates. The data indicate that mucus from channel catfish results in a chemotactic response by F. columnare. This positive chemotactic response may be an important first step for F. columnare colonization of channel catfish skin or gills. Although the role that chemotaxis plays in the virulence of F. columnare is not fully defined, the chemotactic response of genomovar ll isolates suggests that chemotaxis is associated with virulence. [source] Vulnerability of age-0 pallid sturgeon Scaphirhynchus albus to fish predationJOURNAL OF APPLIED ICHTHYOLOGY, Issue 1 2010By W. E. French Summary Stocking is a commonly employed conservation strategy for endangered species such as the pallid sturgeon, Scaphirhynchus albus. However, decisions about when, where and at what size pallid sturgeon should be stocked are hindered because vulnerability of pallid sturgeon to fish predation is not known. The objective of this study was to evaluate the vulnerability of age-0 pallid sturgeon to predation by two Missouri River predators under different flow regimes, and in combination with alternative prey. To document vulnerability, age-0 pallid sturgeon (<100 mm) were offered to channel catfish Ictalurus punctatus and smallmouth bass Micropterus dolomieu in laboratory experiments. Selection of pallid sturgeon by both predators was measured by offering pallid sturgeon and an alternative prey, fathead minnows Pimephales promelas, in varying prey densities. Smallmouth bass consumed more age-0 pallid sturgeon (0.95 h,1) than did channel catfish (0.13 h,1), and predation rates did not differ between water velocities supporting sustained (0 m s,1) or prolonged swimming speeds (0.15 m s,1). Neither predator positively selected pallid sturgeon when alternative prey was available. Both predator species consumed more fathead minnows than pallid sturgeon across all prey density combinations. Results indicate that the vulnerability of age-0 pallid sturgeon to predation by channel catfish and smallmouth bass is low, especially in the presence of an alternative fish prey. [source] Size-specific growth of bluegill, largemouth bass and channel catfish in relation to prey availability and limnological variablesJOURNAL OF FISH BIOLOGY, Issue 1 2007D. E. Shoup Growth of sympatric populations of three important sport fish species: bluegill Lepomis macrochirus, largemouth bass Micropterus salmoides and channel catfish Ictalurus punctatus, in 14 Illinois reservoirs was assessed in an attempt to relate size-specific growth to environmental conditions. Multiple regression relationships for most species and size classes explained a large percentage of the variation in growth. Growth of small bluegill (50 mm total length, LT) showed a strong negative relationship with bluegill catch per unit effort (cpue), per cent littoral area and pH. Large bluegill (150 mm LT) growth was negatively related to Daphnia spp. and benthic macroinvertebrate abundance and lake volume, and positively related to bluegill cpue. Growth of small (100 mm LT) and large (250 mm LT) largemouth bass was not well explained by any of the measured variables. Growth of both small (300 mm LT) and large (450 mm LT) channel catfish was strongly positively related to forage fishes and ichthyoplankton abundance, and per cent littoral area while negatively related to benthic macroinvertebrates. By identifying environmental conditions associated with increased growth rates, these models provide direction for managing fish populations and suggest testable hypotheses for future study of the complex interactions between environmental conditions and growth. [source] Effect of dietary cortisol administration on growth and reproductive success of channel catfishJOURNAL OF FISH BIOLOGY, Issue 3 2004B. C. Small The effect of cortisol administration on reproductive performance was investigated in channel catfish Ictalurus punctatus broodfish. Cortisol was added to a commercial catfish feed by dissolving in ethanol and spraying the feed to yield a dietary concentration of 150 mg kg,1 feed. The cortisol diet and the control (no cortisol) diet were offered at a rate of 1% of biomass to three replicate ponds each containing 28 female and 14 male broodfish, respectively, three times per week for 11 weeks. Spawning began 10 days after the start of the experiment, and continued for 10 weeks. In fish fed cortisol, body mass and the hepato-somatic index were reduced (P , 0·02) and concentrations of plasma cortisol and glucose were significantly higher (P , 0·0003) compared to those of controls. The relative frequency of spawning was similar between the two treatments; however, cortisol-fed channel catfish had an average of 47·1% more spawns than the control-fed fish. On average, there were 25·5 spawns per pond in the treated groups compared to 12·3 spawns per control pond (P = 0·10). No effect was observed on egg production, with individual egg mass, fecundity, and hatching success being similar (P , 0·27) for both treatments. Despite the observed negative effects of cortisol on somatic and hepatic growth, the increased reproductive output coupled with no observable effects on the eggs or hatching success demonstrates that cortisol does not suppress channel catfish reproduction. [source] Evaluation of diquat against an acute experimental infection of Flavobacterium columnare in channel catfish, Ictalurus punctatus (Rafinesque)JOURNAL OF FISH DISEASES, Issue 5 2009A M Darwish Abstract A trial was performed to evaluate the efficacy of diquat (6,7-dihydrodipyrido[1,2-a:2,,1,-c]pyrazinediium dibromide) against an acute experimental infection of Flavobacterium columnare in channel catfish, Ictalurus punctatus. Diquat is an Environmental Protection Agency-approved herbicide and has the potential to be legally and practically used against columnaris. Channel catfish were challenged, by cutaneous abrasion, and waterborne exposure to F. columnare and treated once at 22-h post-challenge with 2.5, 5.0, 10.0 and 15 mg L,1 of diquat active ingredient for 6 h. At the conclusion of the trial, 21-day post-challenge, diquat at 5.0, 10.0 and 15 mg L,1 significantly (P < 0.05) reduced the mortality of infected fish from 95% in the challenged non-treated fish to 68%, 59% and 49%, respectively. In vitro, the minimum inhibitory concentration (MIC) of 23 isolates of F. columnare was assayed. The majority of the isolates had an MIC value of 5 ,g mL,1 (15 of the 23 isolates). Infected fish exhibited acute clinical signs similar to a natural infection. The skin had severe ulcerative necrotizing dermatitis and the muscles had severe necrotizing myositis. The gills had severe multifocal necrotizing branchitis. The results demonstrate that diquat would reduce mortalities caused by an acute columnaris infection. [source] Susceptibility of channel catfish, Ictalurus punctatus (Rafinesque), to Edwardsiella ictaluri challenge following copper sulphate exposureJOURNAL OF FISH DISEASES, Issue 10 2007B R Griffin Abstract Channel catfish, Ictalurus punctatus (Rafinesque), with or without a preliminary 24 h exposure to 2 mg copper sulphate L,1, were challenged with 7.5 × 106 colony forming units L,1 of Edwardsiella ictaluri to determine the effect of copper sulphate on disease resistance. Catfish previously exposed to copper sulphate were significantly more resistant to the bacterial challenge than those not exposed. Catfish not exposed to copper sulphate suffered 35.5% mortality while catfish exposed to copper sulphate experienced 14.1% mortality. Copper concentrations were the same in tank waters of both exposed and control fish at the time of challenge, eliminating the possibility that copper in the water may have been toxic to bacteria. Copper concentrations in freeze dried and ground tissues of unexposed, exposed, and purged channel catfish were highest in fish before copper sulphate exposures suggesting that elevated tissue levels of copper were not responsible for the increased resistance to bacterial challenge. Competition for sites of bacterial attachment to gill or epithelial cells may account for the reduction in mortality; although this is not supported by the low copper content of fish tissue after copper exposure. [source] Induced cross-protection in channel catfish, Ictalurus punctatus (Rafinesque), against different immobilization serotypes of Ichthyophthirius multifiliisJOURNAL OF FISH DISEASES, Issue 3 2006D-H Xu Abstract Channel catfish, Ictalurus punctatus (Rafinesque), were immunized with Ichthyophthirius multifiliis (Ich) theronts and trophonts, and the immune response and host protection against both homologous and heterologous serotypes of Ich were evaluated. Immunizations were done with two immobilization serotypes (ARS4 and ARS6) of live theronts by bath immersion (trial I) and with sonicated trophonts by intraperitoneal (i.p.) injection (trial II). Cutaneous and serum antibody titres against Ich following immunization were measured and survival of catfish was determined after theront challenge. Theronts were immobilized by the antiserum from fish immunized with homologous theronts or trophonts, but not by the serum of fish immunized with the heterologous serotype. Serum from fish immunized by immersion with live theronts showed higher enzyme-linked immunosorbent assay titres against both homologous and heterologous serotypes than fish immunized by i.p. injection of trophonts. Channel catfish immunized by immersion with live theronts or by i.p. injection with sonicated trophonts developed an immune response against Ich and provided cross-protection against challenge from both serotypes (ARS4 and ARS6) of the parasite. Sonicated trophont antigens in aqueous solution by i.p. injection could stimulate an immune response in fish, but the immunity was of short duration. [source] Isolation and characterization of strains of Flavobacterium columnare from BrazilJOURNAL OF FISH DISEASES, Issue 4 2005H C P Figueiredo Abstract Flavobacterium columnare is an important pathogen of freshwater fish, implicated in skin and gill disease, often causing high mortality. An outbreak of skin disease in fingerling and adult Nile tilapia, Oreochromis niloticus (L.), cultivated in a recirculation system, was investigated. Four strains were isolated and characterized by biochemical reactions, enzyme production, fatty acid profile and analysis of the 16S-23S rDNA intergenic spacer region. All strains were identified as F. columnare. Experimental infection assays with one of these strains (BZ-5-02) were conducted and pathogenicity (by intramuscular route) was demonstrated in Nile tilapia and channel catfish, Ictalurus punctatus (Rafinesque). This is the first report of characterization of Brazilian strains of F. columnare. [source] Immune responses and host protection of channel catfish, Ictalurus punctatus (Rafinesque), against Ichthyophthirius multifiliis after immunization with live theronts and sonicated trophontsJOURNAL OF FISH DISEASES, Issue 3 2004D-H Xu Abstract The humoral immune responses and host protection of channel catfish, Ictalurus punctatus (Rafinesque), against Ichthyophthirius multifiliis (Ich) were determined after immunization with live theronts and sonicated trophonts. Immunizations with live theronts or sonicated trophonts were carried out by both bath immersion and intraperitoneal (i.p.) injection. Cutaneous and serum immunoglobulin (Ig) levels and anti-Ich antibodies were measured 12 and 21 days post-immunization. The level of Ich infection and survival of catfish were determined after theront challenge. Cutaneous and serum anti-Ich antibodies were significantly higher (P < 0.05) in fish immunized with live theronts by immersion or i.p. injection, or with sonicated trophonts administered by i.p. injection, than in fish immunized with sonicated trophonts by immersion, with bovine serum albumin by i.p. injection, or non-immunized controls. Host protection was noted only in fish immunized with live theronts by immersion or i.p. injection or with sonicated trophonts by i.p. injection. There was a positive correlation between higher levels of anti-Ich antibodies and host survival in the immunized fish. [source] Acute columnaris infection in channel catfish, Ictalurus punctatus (Rafinesque): efficacy of practical treatments for warmwater aquaculture pondsJOURNAL OF FISH DISEASES, Issue 1 2004S Thomas-Jinu Abstract Columnaris disease was induced in channel catfish, Ictalurus punctatus (Rafinesque), by bath exposure to four highly virulent isolates of Flavobacterium columnare. In untreated controls, mortality began 20 h after exposure and reached 100% by 48 h. Mortality in channel catfish given antibiotic treatments with oxytetracycline or a combination of sulphadimethoxine and ormetoprim in feed prior to bacterial challenge was zero with all four strains of F. columnare. Diquat® (Zeneca Agricultural Products, Wilmington, DE, USA) was the most effective bath treatment; mortality with all four strains was zero. With potassium permanganate, chloramine-T, hydrogen peroxide and copper sulphate, bath treatment efficacy varied significantly among strains (P = 0.0346) and among treatments (P = 0.0033). Bath treatments with chloramine-T and potassium permanganate significantly reduced (P < 0.05) mortality from 100 to 75 and 69%, respectively, but copper sulphate and hydrogen peroxide treatments were not effective. Based on our results, oral antibiotics prevented columnaris disease but, of the bath treatments, only Diquat® produced a dramatic reduction in the mortality of acutely infected fish. Diquat® is labelled for aquatic use as an herbicide in the USA but in large ponds it is prohibitively expensive. [source] Comparative challenge model of Flavobacterium columnare using abraded and unabraded channel catfish, Ictalurus punctatus (Rafinesque)JOURNAL OF FISH DISEASES, Issue 8 2003J A Bader Abstract The early entry of the fish pathogen Flavobacterium columnare and enhancement by abrasion was studied in channel catfish, Ictalurus punctatus (Rafinesque), using the polymerase chain reaction and a species-specific primer set for a bacterial 16S rRNA gene product. Evaluations were conducted following an abrasion bath immersion challenge with F. columnare. Abrasion, a practice which has historically been used prior to bacterial challenge, had significant effects on the early entry of the pathogen and on cumulative percent survival (CPS). The FvpF1,FvpR1 primer set was useful in detecting the early entry of F. columnare in mucus, skin, gill, blood, liver and trunk kidney tissues in both abraded and unabraded fish following immersion challenge at 29 ± 2 °C. Bacteria were detected earlier in all tissues in abraded fish, except in the trunk kidney. These differences were not significant, except in the case of blood. Mucus, skin and gill tissues were positive for F. columnare earliest regardless of treatment (after 5 min in abraded fish and after 15 min in unabraded fish). CPS following challenge with F. columnare was significantly affected by abrasion, which supports the use of abrasion for the F. columnare challenge model for channel catfish. [source] Evidence that channel catfish, Ictalurus punctatus (Rafinesque), mortality is not linked to ingestion of the hepatotoxin microcystin-LRJOURNAL OF FISH DISEASES, Issue 5 2002G S Snyder Catfish farms located in the south-eastern USA using brackish (3,5 g NaCl L,1) well water experience sporadic fish kills sometimes with high mortality. An investigation of three catastrophic losses occurring in this region identified no involvement of infectious diseases or traditional water quality problems, including oxygen, ammonia or nitrite. The high mortality and time course of the problem was indicative of exposure to a toxin. Attempts by other workers to explain the cause of this unique syndrome (high chloride associated toxicosis of catfish, HCTC), suggested that the losses might be because of microcystin-producing blooms of Microcystis aeruginosa, but our investigations failed to support this conclusion. We found that (1) the liver histology of catfish experimentally exposed to pure microcystin-LR is very different from that of catfish sampled during outbreaks of HCTC; (2) measurements of microcystin-LR concentrations in the three cases were far lower than the concentration required to kill catfish by experimental immersion; (3) the HCTC toxin appears to have a short half-life, whereas microcystin-LR does not; (4) experimental gavage of catfish with massive amounts of microcystin-LR does not cause the acute mortality typical of HCTC; (5) outbreaks of HCTC appear to be associated with heavy blooms of Anacystis marina, a halophytic cyanobacteria, not with blooms of M. aeruginosa. [source] Does Pond Water Reflectance Influence Double-crested Cormorant Selection of Aquaculture Ponds?JOURNAL OF THE WORLD AQUACULTURE SOCIETY, Issue 3 2010Andrew A. Radomski Double-crested cormorants, Phalacrocorax auritus, are a frequent and major avian predator on channel catfish, Ictalurus punctatus, and other aquaculture species throughout the southeastern USA. Although cormorant movements and occurrence within the aquaculture production region are understood, no studies have focused on the mechanisms utilized by these avian predators to select foraging sites within these high-density aquaculture systems. The objective of this study was to determine if cormorant abundance is associated with specific (ultraviolet to visible) light reflectance spectra within commercial catfish ponds. Three commercial farms were used in this study; each farm had four ponds classified as "preferred" and another four ponds classified as "avoided" based on observing cormorant numbers for 3 mo prior to reflectance measures (>100 h observation for each pond). Reflectance and pond turbidity were measured weekly for 7 wk during the period of maximal over-wintering cormorant numbers. Water samples were collected at the surface (1 cm depth) and secchi depth (10,41 cm) at two locations (upwind and downwind sides) within each pond to determine spectral reflectance and turbidity. Average pond reflectance values were not significantly different between ponds preferred and avoided by cormorants; however, upwind reflectance significantly differed from downwind reflectance between cormorant use groups. Using cross-validation discriminant analysis, the accuracy of separating upwind ponds preferred and avoided by cormorants was over 62%. Repeated measures ANOVA identified the reflectance at 370, 380, 460, 500, 510, and 620 nm as significantly different between ponds preferred and avoided by cormorants. The lower wavelengths (380,410 nm) correspond to known UV-A sensing compounds in cormorants and the other wavelengths share characteristics associated with algal biomass. Cormorants utilize ponds that have lower algal biomass when compared with avoided ponds. [source] | |||||||||||||