Distribution by Scientific Domains

Kinds of Tilapia

  • adult nile tilapia
  • hybrid tilapia
  • juvenile hybrid tilapia
  • juvenile nile tilapia
  • juvenile tilapia
  • male tilapia
  • nile tilapia

  • Terms modified by Tilapia

  • tilapia Oreochromi niloticu
  • tilapia culture
  • tilapia diet
  • tilapia fillet
  • tilapia production
  • tilapia production system
  • tilapia species

  • Selected Abstracts


    Lipid peroxidation was analyzed in muscle and sarcoplasmic reticulum (SR) of hybrid tilapia fed diets containing 0, 100, 200, and 300 IU vitamin E/kg for 8 months. Iron-catalyzed NADH-dependent lipid peroxidation in SR of tilapia fed diet containing no supplemented vitamin E was significantly greater than that of fish fed other diets (P < 0.05). No difference was observed in SR lipid peroxidation between fish fed 200 and 300 IU vitamin E/kg. Thiobarbituric acid reactive substances (TBARS) produced in muscle stored at either 4C or -40C for 7 days and 8 weeks, respectively, increased when storage time increased. When muscle TBARS were plotted against storage time, the lag phases were longer for fish fed high vitamin E (, 200 IU/kg) diets than those from fish fed low vitamin E diets. [source]


    ABSTRACT Recent development in magnetic carrier technology involves the use of nonmagnetic substrates attached to superparamagnetic particles forming functionally modified magnetic support to isolate a particular enzyme in a controllable magnetic field. In this study, the superparamagnetic particles were modified by epichlorohydrin and other agents to cross-link with starch to form the purification support. This affinity support was able to bind the amylase and was used in the purification of amylase from Taiwan tilapia. After ammonium sulfate precipitation of amylase from Taiwan tilapia, the modified superparamagnetic particles were able to purify the crude amylase by 20.78-fold with recovery of activity of 75.6%. The molecular weight of the amylase was estimated to be 66.1 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Both crude and purified amylase reached an optimum at a pH of 8.0 and temperature of 50C, and the enzyme was stable between 20 and 50C. PRACTICAL APPLICATIONS Because of the rapid development of high technology such as carrier supports for enzyme purification, the development, research and application of magnetic carriers are timely needed. The present study demonstrated that the affinity superparamagnetic particles could be used as a carrier support to absorb and purify the amylase and that technology of affinity purification can be widely used in protein purification. Compared with the traditional chromatography used in the purification of proteins, this novel affinity superparamagnetic particle technology is rapid, has low operation cost, requires simple facilities, and involves easy separation and recovery of the enzymes. [source]

    Genotoxicity testing of the herbicide trifluralin and its commercial formulation Treflan using the piscine micronucleus test

    Serpil Könen
    Abstract In this study, the genotoxic effects of a widely used herbicide, trifluralin, and its commercial formulation, Treflan, were evaluated using the micronucleus test in a commercially important fish species, Oreochromis niloticus (Nile Tilapia). Fish were exposed to 1, 5, and 10 ,g/L doses of trifluralin and Treflan for 3, 6, and 9 days under laboratory conditions. Ethylmethanesulfonate, at a single dose of 10 mg/L, was used as positive control. Micronuclei were evaluated on the peripheral erythrocytes. Both Treflan and trifluralin treatments significantly increased the micronucleus frequencies in peripheral erythrocytes of O. niloticus. Furthermore, the genotoxicity of the active ingredient, trifluralin, was observed to be higher than that of the commercial formulation Treflan. Our results indicate that herbicide trifluralin has genotoxic potential in fish. Environ. Mol. Mutagen., 2008. © 2008 Wiley-Liss, Inc. [source]

    The effect of Pediococcus acidilactici on the gut microbiota and immune status of on-growing red tilapia (Oreochromis niloticus)

    R.M.W. Ferguson
    Abstract Aim:, To assess Pediococcus acidilactici as a dietary supplement for on-growing red tilapia (Oreochromis niloticus). Methods and Results:, Tilapia were fed either a control diet or control diet supplemented with Ped. acidilactici at 107 CFU g,1 for 32 days. Ped. acidilactici colonized the intestinal tract and significantly affected the intestinal microbial communities. PCR-DGGE revealed direct antagonism of gastric Ped. acidilactici with an endogenous uncultured bacterium during a period of reverting to nonsupplemented feeding. Light microscopy revealed that gut integrity and leucocyte levels were unaffected by Ped. acidilactici; however, blood leucocyte levels and serum lysozyme activity were elevated after 14-days' feeding. No significant improvements in growth performance were observed at the end of the trial (day 32), but survival was significantly higher in the probiotic group. Conclusions:, The study demonstrates that oral supplementation of Ped. acidilactici modulates intestinal bacterial communities in on-growing red tilapia and also stimulates some aspects of the nonspecific immune response. Significance and Impact of the study:, To our knowledge this is the first study assessing the effects of probiotics on the gut microbiota of tilapia using culture-independent methods. Such methods are crucial to understand the mechanisms which underpin and mediate host benefits. [source]

    Modelling and predicting the effect of temperature, water activity and pH on growth of Streptococcus iniae in Tilapia

    K. Zhou
    Abstract Aims:, To evaluate and model the growth of Streptococcus iniae affect by temperatures (10,45°C), water activity (Aw; 0·995,0·957), and pH (5,8). Methods and Results:, Temperatures, Aw, and pH were adjusted. The behaviour of S. iniae was studied and modelled. Growth curves were fitted by using logistic, Gompertz, and Baranyi models. The maximum growth rates obtained from the primary model were then modelled as a function of temperature, Aw, and pH using the Belehradek-type models for secondary model. The optimum values for growth were found to be in the range of 35,40°C, Aw 0.995,1, and pH 6,7. The statistical characteristics of the models were validated by r2, mean square error, bias, and accuracy factors. The results of validation indicated that Baranyi model performed the best. Conclusions:, The effect of temperature, Aw/NaCl, pH control of S. iniae in tilapia could be satisfactorily predicted under current experimental conditions, and the proposed models could serve as a tool for this purpose. Significance and Impact of the Study:, The suggested predictive model can be used for risk assessment concerning S. iniae in tilapia. [source]


    ABSTRACT To delay lipid oxidation during meat processing, synthetic antioxidants have been used in the food industry, but the consumers' concern over their toxicity increased interest in research with natural antioxidants. The aim of this work was to analyze the water activity (Aw), thiobarbituric acid reactive substances (TBARS), moisture and trichloroacetic acid-soluble nitrogen (TCASN) in brined tilapia fillets treated or pretreated with natural rosemary extract (Rosmarinus officinalis) and stored for 240 days at ,18C. Higher Aw (0.900 ± 0.010) and moisture (70.13 ± 0.20) values were observed in the pretreated fillets. The TBARS values in the treatment (3.31 ± 0.79) and pretreatment (3.39 ± 0.53) were half the value of the control treatment (6.14 ± 1.21) at 240 days. Statistical differences were observed in TCASN values in 180 (0.112 ± 0.020) and 240 (0.132 ± 0.017) days, with the pretreatment showing a more protective effect in protein oxidation. In this study, rosemary proved to be protective during the frozen storage, especially when its extract was used as pretreatment, before the salting process. PRACTICAL APPLICATIONS Fish consumption is highly elastic, because the annual average consumption of seafood per person in Brazil is only 6.8 kg. The federal government has set a goal to increase it to 12 kg by 2007. Salting is an older food preservation process still used today, and is extremely important because, despite advances in food technology, increased monitoring and improved knowledge, it is emphasized as an easy, cheap and effective process that does not require refrigeration. Tilapia is a highly prolific fish, with a production volume that is increasingly higher each year in Brazil. Therefore, it calls for interesting research to allow an increased shelf life for this species. [source]

    Temperature Influences the Ontogenetic Expression of Aromatase and Oestrogen Receptor mRNA in the Developing Tilapia (Oreochromis mossambicus) Brain

    C. -L.
    Abstract Water temperature has a differential influence on the development of central neurotransmitter systems according to the developmental period in tilapia (Oreochromis mossambicus). Aromatase and oestrogen receptors (ERs) represent important components of the mechanism of brain differentiation. Gene expression of aromatase and ERs is modulated by neurotransmitters in the developing brain. In the present study, the quantitative reverse transcription-polymerase chain reaction method was used to investigate the effects of temperature on the ontogenetic expression of aromatase and ERs in the developing tilapia brain. Before day 10 posthatching, exposure to a higher temperature (32 °C) resulted in a significant increase in the expression of brain aromatase; conversely, a lower temperature (20 °C) resulted in a decrease. ER, expression was depressed in accordance with the decrease of temperature, but ER, was unaffected by temperature. Between days 10 and 20, neither brain aromatase nor ER, expression was altered by temperature, whereas ER, expression was significantly enhanced by exposure to 32 °C. Between days 20 and 30, brain aromatase significantly increased at the higher temperature and decreased at 20 °C, but neither ER, nor ER, was affected by temperature. The expression of both brain aromatase and ERs, differentially regulated according to the temperature and to the developmental period, could be related to brain,sex differentiation. [source]

    Growth Performance, Immune Response, and Resistance to Streptococcus iniae of Nile Tilapia, Oreochromis niloticus, Fed Diets Containing Various Levels of Vitamins C and E

    Chhorn Lim
    Growth, immunity, and resistance of Nile tilapia to Streptococcus iniae challenge were evaluated after feeding diets supplemented with vitamin C (0, 100, 2000 mg/kg) and E (0, 50, 500 mg/kg) for 12 wk. Supplementation of 100 mg vitamin C/kg to the basal diet was sufficient to increase growth and feed efficiency. The amount of vitamin E present in the basal diet (23.1 mg/kg) was sufficient to promote good growth and feed efficiency, but adding 50 mg vitamin E/kg was necessary to increase survival. Liver vitamin C and E concentrations increased with increasing dietary concentrations of the corresponding vitamin. Dietary vitamin E concentrations had no effect on liver vitamin C concentration, but increasing dietary vitamin C increased liver vitamin E. Although hematology was generally unaffected by dietary vitamin E, significantly lower red blood cell count and hemoglobin and higher mean corpuscular volume were observed in fish fed the vitamin C-unsupplemented diets. Total immunoglobulin and lysozyme activity were significantly higher and lower, respectively, in fish fed 2000 mg/kg vitamin C diets. Vitamin E at 500 mg/kg diet significantly decreased alternative complement activity. Dietary concentrations of vitamin C had no effect on mortality following S. iniae challenge, but mortality significantly decreased in fish fed vitamin E,supplemented diets. [source]

    Interaction of Phytochemical-Quercetin with the Other Antioxidant, Ascorbic Acid and their Protective Effect in Tilapia after Ultraviolet Irradiation

    Gustavo A. Rodriguez-Montes De Oca
    Semi-purified, casein-gelatin-based diets were prepared and supplemented with quercetin (Q) and/ or ascorbic acid (AA): control diet C,Q,(100 mg/kg AA), diet C ,Q+ (100 mg/kg AA + quercetin 10 g/kg), diet C +Q, (1000 mg/kg AA), and diet C +Q+ (1000 mg/kg AA + quercetin 10 g/kg). These diets were fed to tilapia for 19 wk and then fish were divided into controls and ultraviolet (UV) treatments. Fish were exposed to UV radiation. Control groups were protected with a MYLAR® polyester film and plexiglass. At week 20, the same fish were re-exposed to UV radiation. Control groups of fish were protected by a double layer of MYLAR® and the UV groups were exposed with no protection. Before UV exposure, 24 h after, and 7 d after the second treatment, fish liver and skin were dissected for Q and AA analyses. The proportion of oxidized ascorbate was significantly increased in fish from treatments C ,Q, and C ,Q+ . Q concentrations in fish after exposures were negligible in skin, whereas liver concentrations were significantly different among control (34 ± 10 ,g/g) and UV-irradiated fish (11 ± 6 ,g/g), respectively. The interaction between these two dietary antioxidants may change after chronic UV irradiation. [source]

    The Effects of Dietary Yeast Culture or Short-chain Fructo-oligosaccharides on the Intestinal Autochthonous Bacterial Communities in Juvenile Hybrid Tilapia, Oreochromis niloticus,×Oreochromis aureus,

    Zhi-Gang Zhou
    The effects of dietary yeast culture (YC) or short-chain fructo-oligosaccharides (FOS) on intestinal autochthonous bacterial communities in juvenile hybrid tilapia, Oreochromis niloticus,×Oreochromis aureus, were studied by 16S rDNA denaturing gradient gel electrophoresis (DGGE). Ninety Tilapias in tanks (10 fish per tank) were randomly and equally divided into three groups. At the end of an 8-wk feeding period of CK (the control treatment), YC (3 g/kg), or FOS (1 g/kg), autochthonous gut bacteria were analyzed in intestinal samples of all fish in each tank of a recirculating aquaculture system. The clear differences in the banding patterns indicated the obvious effects of dietary prebiotics on intestinal communities in hybrid tilapia. Higher variation was detected within the dietary YC group. This difference might be due to the effects of certain immune-stimulating agents in YC on the immunity response of hybrid tilapia. It was concluded that dietary prebiotics, YC, and FOS obviously affected the intestinal bacterial community in hybrid tilapia with different patterns for different kinds. [source]

    Evaluation of Alternative Protein Sources to Replace Fish Meal in Practical Diets for Juvenile Tilapia, Oreochromis spp

    Tri N. Nguyen
    Two feeding experiments were conducted to evaluate if methionine is limiting in practical grow-out diets for tilapia, Oreochromis spp. Four diets containing 32% protein and 5% lipid were designed to compare the use of diets high in dehulled solvent-extracted soybean meal (DSESM) and expeller pressed soybean meal (EPSM) compared with a diet containing 6% fish meal (FM). Tilapia (4.78 ± 0.07 g, mean ± SD) were randomly stocked into twelve 600-L flow-through tanks at 20 fish per tank. After 6 wk, there were no notable trends or statistically significant differences (P > 0.05) in final mean weight, survival rate, and feed conversion ratio (FCR) among the treatments. Because results of this study indicated that DSESM could totally replace FM in practical diets for juvenile tilapia, a second batch of diets were formulated using other protein sources. Typical levels of cottonseed meal (CSM), DSESM, and meat and bone meal (MBM) were used to evaluate whether methionine could be limiting. Two basal diet formulations were tested either without or with methionine supplement (0.06/100 g diet). The first diet contained 15% CSM, 27% DSESM, and 10% MBM and the second diet contained 15% CSM and 37% DSESM. These diets contained 28% protein and 5% lipid. Tilapia (3.90 ± 0.05 g) were randomly stocked into twelve 60-L glass aquaria of a recirculation system at 18 fish per aquarium for 5 wk and then moved to the 600-L flow-through tanks for five more weeks. After 10 wk, there were no statistically significant differences (P > 0.05) in final mean weight, survival rate, and FCR among the four treatments. Results of the present study indicated that DSESM and EPSM could totally replace FM's inclusion rate in commercial diets for juvenile tilapia. Furthermore, methionine did not appear to be limiting in practical diets using typical levels of CSM, DSESM, and MBM as primary protein sources. [source]

    Feeding Dietary Mannan Oligosaccharides to Juvenile Nile Tilapia, Oreochromis niloticus, Has No Effect on Hematological Parameters and Showed Decreased Feed Consumption

    Ricardo Yuji Sado
    Impaired immune system by environmental stressors can lead fishes to be more susceptible to diseases that limit the economic development of aquaculture systems. This study was set out to determine the effect of six levels of mannan oligosaccharides (MOS; ActiveMOS®; Biorigin, Lençois Paulista, São Paulo, Brazil) on the performance index and hematology of Nile tilapia, Oreochromis niloticus juveniles. Fish (13.62 g) were randomly distributed into 18 plastic aquaria (300 L; 20 fishes per aquarium) and fed during 45 d with a commercial diet supplemented with 0, 0.2, 0.4, 0.6, 0.8, and 1% dietary MOS, in a totally randomized design trial (n = 3); biometrical and hematological data were collected and analyzed. There were no significant differences in hematological parameters between fish fed control and MOS supplementation diets, and daily feed consumption (FC) decreased (P < 0.05) with increasing levels of dietary MOS. Dietary MOS did not increase leukocyte count and presented negative effects on FC of Nile tilapia. At 0.4% MOS supplementation, the individual weight gain was higher in absolute values but not different (P > 0.05) compared to control diet. [source]

    Evaluation of Brewer's Waste as Partial Replacement of Fish Meal Protein in Nile Tilapia, Oreochromis niloticus, Diets

    Desale B. Zerai
    A 10-wk feeding trial experiment involving five different diets with increasing levels of brewer's waste (32% crude protein) was carried out to evaluate the use of brewer's waste in tilapia diets in place of fish meal. Growth performance was compared against a control diet formulated to have similar composition to a typical commercial diet. Four experimental diets replaced successively 25, 50, 75, and 100% of the fish meal protein with brewer's waste. The diets were isonitrogenous and isocaloric. Results indicated that weight gain did not differ significantly (P > 0.05) with up to 50% replacement. Feed intake and utilization were depressed at high levels of brewer's waste. In addition, methionine of high replacement level diets was low. The results of the digestibility trial demonstrated that the brewer's waste used in this study has an apparent digestibility coefficient for protein of 70%. It was concluded that 50% of the fish meal protein in a typical commercial diet could be replaced with brewer's waste with no adverse effect on growth and feed utilization for tilapia. [source]

    Effects of Two Densities of Caged Monosex Nile Tilapia, Oreochromis niloticus, on Water Quality, Phytoplankton Populations, and Production When Polycultured with Macrobrachium rosenbergii in Temperate Ponds

    Jason J. Danaher
    The effects of different densities of caged Nile tilapia, Oreochromis niloticus, on water quality, phytoplankton populations, prawn, and total pond production were evaluated in freshwater prawn, Macrobrachium rosenbergii, production ponds. The experiment consisted of three treatments with three 0.04-ha replicates each. All ponds were stocked with graded, nursed juvenile prawn (0.9 ± 0.6 g) at 69,000/ha. Control (CTL) ponds contained only prawns. Low-density polyculture (LDP) ponds also contained two cages (1 m3; 100 fish/cage) of monosex male tilapia (115.6 ± 22 g), and high-density polyculture (HDP) ponds had four cages. Total culture period was 106 d for tilapia and 114 d for prawn. Overall mean afternoon pH level was significantly lower (P , 0.05) in polyculture ponds than in CTL ponds but did not differ (P > 0.05) between LDP and HDP. Phytoplankton biovolume was reduced in polyculture treatments. Tilapia in the LDP treatment had significantly higher (P , 0.05) harvest weights than in the HDP treatment. Prawn weights were higher (P , 0.05) in polyculture than prawn monoculture. These data indicate that a caged tilapia/freshwater prawn polyculture system may provide pH control while maximizing pond resources in temperate areas. [source]

    Physiological Responses of Nile Tilapia, Oreochromis niloticus, Fed Vitamin C- and Lipid-Supplemented Diets and Submitted to Low-Temperature Stress,

    Dario R. Falcon
    This study evaluated the effects of different levels of vitamin C and lipids on physiological responses of Nile tilapia, Oreochromis niloticus, submitted to temperature stress. There were two phases: Phase I , preparing fish to store vitamin C and lipid at appropriate temperature, and Phase II , evaluating the contributions these reserves make to fish physiology under low-temperature stress. The experiment used a 3 × 2 factorial design with three vitamin C levels (300, 600, and 1200 mg/kg diet) and two lipid levels (8.0 and 12.0%), plus absence of nutrient test and a diet of 6.0% lipids and 125.0 mg/kg vitamin C. In Phase I, 192 fish were kept at 26.0 ± 1.0 C for 112 d, and in Phase II, 48 fish were kept at 18.0 ± 0.5 C for 32 d and at 15.0 ± 0.5 C for 11 d. Fish fed C0L0 diet showed lower erythrocytes values in both phases; higher vitamin C supplement determined higher red blood cell (RBC) number and higher hematocrit (Htc) (Phase II); Htc was significantly lower in Phase II; after temperature stress, fish fed C0L0 diet had higher mean corpuscular volume, lower hemoglobin corpuscular concentration, and significantly lower vitamin C concentration in the liver; and higher supplementation determined a higher concentration in the liver (Phases I and II). Higher plasmatic cortisol concentration was seen in fish fed C0L0 diet. In conclusion, our results show that the absence of vitamin C in diets impairs RBC formation and does not enable fish to cope with stress; excess vitamin C is efficient in mitigating stress and 600 mg/kg diet is economic and physiologically sufficient to prepare fish for coping with low-temperature stress. Lipid supplementation does not determine alterations in stress biochemical parameters. [source]

    Economic Analysis of Nile Tilapia (Oreochromis niloticus) Production in Tanzania

    Aloyce R Kaliba
    In Tanzania, Nile tilapia culture is a promising aquaculture enterprise. Information on production costs could assist fish farmers in economic and financial planning. Economic profitability of small-scale Nile tilapia production in Tanzania is analyzed using a model that simulates individual fish growth and takes into account fish population dynamics in the pond. The results suggest that the current practiced mixed-sex tilapia culture without predation is not economically sustainable. Extension efforts should be geared toward developing a Nile tilapia production system that is based on a hand-sexed all-male tilapia. Meanwhile catfish can be introduced in ponds to control overcrowding in mixed-sex tilapia culture without predation. Studies to determine optimal pond sizes, availability of feed, and a quality fingerling supply chain are also fundamental for developing a sustainable Nile tilapia production system in Tanzania. Under improved Nile tilapia production systems, returns are high enough to justify investment through borrowed capital from formal institutions. [source]

    Evaluation of Growth Performance of Nonimproved and Improved Strains of the Nile Tilapia (L.), Oreochromis niloticus

    Mohammad T. Ridha

    Efficacy of an experimentally inactivated Streptococcus agalactiae vaccine in Nile tilapia (Oreochromis niloticus) reared in Brazil

    Lucienne Garcia Pretto-Giordano
    Abstract Tilapia aquaculture is one of the fastest-growing segments of fish production in Brazil. Nile tilapia (Oreochromis niloticus) is largely cultivated in the state of Parana, where Streptococcus agalactiae is the cause of severe disease outbreaks. The objective of this paper was to evaluate an inactivated S. agalactiae vaccine in tilapia for the control of streptococcal disease outbreaks. Tilapia, weighing approximately 20 g each, were intraperitoneally (i.p.) inoculated with 0.1 mL of the vaccine at a dose of 2.0 × 108 colony-forming unit (CFU) mL,1. One group of tilapia (treatment 1) received one vaccine dose, and the other group of tilapia (treatment 2) received two doses, with an interval of 21 days. The control group was i.p. inoculated with 0.1 mL tryptic soy broth fish,1. Immunized and control tilapia were i.p. challenged with 0.1 mL of 3.0 × 107 CFU mL,1 at 30 days post vaccination. The fish were monitored daily for disease signs and for mortality for 16 days post challenge. A statistically significant difference (P=0.0045) was found between the mortality of treatments 1 and 2. The value of relative per cent of survival of 83.6% and 96.4%, respectively, indicate that this vaccine was efficient in Nile tilapia. [source]

    Growth, salinity tolerance and microsatellite analysis of the F2 reciprocal hybrids of Oreochromis niloticus×Sarotherodon galilaeus at different salinities

    Biao Yan
    Abstract Oreochromisniloticus (O), the sixth generation of Genetic Improvement of Farmed Tilapia, shows rapid growth but poor salt tolerance, while Sarotherodon galilaeus (S) exhibits opposite traits. To combine the traits, F1 progeny was obtained through artificial fertilization. Fertile F1 produced F2 by natural spawning. The mean survival times, the median survival time (ST50) or the survival rate of hybrids was greater than O. niloticus in a gradual or an acute salinity change. Plasma osmolarity, [Na+] and [Cl,] of the hybrids fluctuated in 32 g L,1 water during a 24-h period, but eventually reached levels similar to fish in freshwater. O. niloticus,×S. galilaeus, (OS F2) or S. galilaeus,×O. niloticus, (SO F2) showed the fastest growth at 22.5 g L,1, equal to about 78.2% or 69.7% of O. niloticus at 0 and 3.87 or 3.45 times that of S. galilaeus at their individual optimum growth. Growth in OS F2 was 12% faster than SO F2. Microsatellite analysis showed that F2 had more alleles, a higher polymorphism information content and greater observed and expected heterozygosity than O. or S. Population differentiation was not detected between F1 and F2. All the results indicated that F2 could be exploited for commercial production under saline conditions. [source]

    The effect of the introduction of Nile tilapia (Oreochromis niloticus, L.) on small indigenous fish species (mola, Amblypharyngodon mola, Hamilton; chela, Chela cachius, Hamilton; punti, Puntius sophore, Hamilton)

    Sultanul Arafin Shemeen Ahmad
    Abstract This is the first controlled experiment to quantify the effect of introduced tilapia on indigenous species. This experiment was conducted in small earthen ponds (100 m2) to assess the impact of mixed-sex or all-male Nile tilapia (Oreochromis niloticus) on small indigenous species (SIS) commonly found in south Asia, mola (Amblypharyngodon mola), chela (Chela cachius) and punti (Puntius sophore). Ponds were fertilized, then stocked with 0.56 fish m,2 of water surface area in the mixed-sex and all-male tilapia treatments and 0.42 fish m,2 in the treatment without tilapia. No additional nutritional inputs were applied after stocking. Treatments were: mixed-sex tilapia with SIS, mono-sex male tilapia with SIS and SIS without tilapia (control). All treatments were stocked with 14 fish per species. All species reproduced during the 21-month culture duration. The number of recruits varied by species, Tilapia reproduced in greater numbers than SIS. Tilapia numbers at harvest were the highest (451 ± 25/100 m2) in the mixed-sex treatment compared with mola (221 ± 22/100 m2), chela (94 ± 8/100 m2) and punti (100 ± 7/100 m2). The number of mola was higher (399 ± 33/100 m2) in the all-male tilapia treatment. There was reduction in the number of mola and chela in the treatment containing mixed-sex tilapia. Gut content analysis combined with water sampling revealed that all fish species fed selectively. Significant interspecies dietary overlap was found between Nile tilapia and SIS and among SIS. Thus, there is potential for tilapia to compete with indigenous fish species when space and other resources are limiting, but a longer duration study with varying level of management is needed to determine how successfully tilapia competes with locally adapted SIS. [source]

    Discrimination of tilapia species of the genera Oreochromis, Tilapia and Sarotherodon by PCR-RFLP of 5S rDNA

    Juliano Toniato
    First page of article [source]

    Effect of dietary protein regime during the growing period on growth performance, feed utilization and whole-body chemical composition of Nile Tilapia, Oreochromis niloticus (L.)

    Mohsen Abdel-Tawwab
    Abstract This study was conducted to evaluate the effect of various dietary protein regimes on growth performance, feed utilization and whole-body chemical composition of Nile tilapia, Oreochromis niloticus (L.). Twenty cages (1 m3 each) were randomly allocated to a four-replicate experiment to represent five treatments (T1,T5) where fish were randomly stocked at a rate of 50 fish (1.5,2.2 g) per cage. Fish in T1,T5 fed on a 45% crude protein (CP) diet for the first 4 weeks. In T1, T2 or T3 fish fed on 45%, 35% or 25% CP diets for the last 8 weeks respectively. In T4 fish fed 35% CP diet for the second 4 weeks followed by 25% CP diet for the last 4 weeks and in T5 fish fed 25% CP diet for the second 4 weeks followed by 35% CP diet for the last 4 weeks. Diets were offered to satiation and provided manually twice a day in the morning and in the afternoon, 6 days a week. The optimum fish growth and feed utilization were obtained at T1, T2 and T4. Protein efficient ratio and apparent protein utilization were lower at T1 and T2 than those of T3,T5. On the other hand, no significant changes in energy utilization were observed among the different treatments. There were no major changes in the carcass composition except in ash content, which was higher in T3 and T5 only. This study recommended that the dietary protein regime is an important management in tilapia culture, and the protein level could be reduced from 45% to 35% then to 25% on increasing the fish size. [source]

    Influence of dietary l -carnitine on growth, biological traits and meat quality in Tilapia

    Shuenn-Der Yang
    Abstract This study was designed to determine whether l -carnitine supplementation is necessary in a tilapia diet containing low-fish meal and a high lipid level, which is beneficial economically and for the environment. The effects of dietary l -carnitine on the growth, body composition, blood traits and post-thaw drip from muscle in hybrid tilapia were investigated. Five isonitrogenous and isocaloric diets were fed to the fish with a mean body weight of 141.7 g for 168 days. The control diet contained fish meal as the major protein source with 7% lipid. Other diets contained 7% or 12% lipid, in which fish meal was largely replaced by plant proteins, and supplemented with l -carnitine or not. Results showed that supplemental dietary l -carnitine did not affect the growth performance, feed efficiency or protein efficiency ratio, while the supplementation significantly reduced the mesenteric fat ratio. Whole body and muscle proximate compositions were unaltered by any dietary treatment. The total plasma lipid, triacylglycerol and cholesterol values of tilapia fed diets with alternative plant proteins were significantly lower than those of the control fish, whereas increasing the dietary lipid content increased the aforementioned blood traits. A decrease in plasma ammonia and an increase in urea were observed in dietary l -carnitine-supplemented fish. Post-thaw drip from muscle was reduced in fish fed supplemental dietary l -carnitine. The observations of this study revealed that neither the growth performance nor the feed utilization of hybrid tilapia was improved by a dietary l -carnitine treatment, but that it did lead to a reduced mesenteric fat ratio, altered nitrogen metabolism and improved meat quality. [source]

    Growth response and acquired resistance of Nile tilapia, Oreochromis niloticus (L.) that survived Streptococcus iniae infection

    Craig A Shoemaker
    Abstract This study determined the growth performance and acquired resistance of Nile tilapia, Oreochromis niloticus (L.) that survived Streptococcus iniae infection. Tilapia were challenged with three doses of S. iniae (8.8 × 103, 8.8 × 104 and 8.8 × 105 CFU fish,1 for low, medium and high challenges respectively). Groups of non-injected and tryptic soy broth-injected fish were maintained as controls. Significantly (P<0.05) higher mortality (45.0%) occurred in the high challenge treatment than in the low challenge treatment group (29.6%). The medium challenge group had mortality (36.3%) that did not differ significantly from the high or low treatment. Few fish died in the non-injected and broth-injected treatments (3.4% and 0.8% respectively). The tilapia that survived S. iniae infection used to assess growth performance were selected from survivors without gross clinical signs of disease. These fish were randomly stocked at a rate of 30 fish into each 57 L aquarium in triplicate and fed to apparent satiation for 8 weeks. No significant differences were detected in weight gain, feed intake, feed efficiency ratio or survival between S. iniae -survived tilapia and the control treatments following the 8-week growth performance trial. Following the 8-week feeding study, tilapia were challenged with 1 × 106 CFU fish,1 of S. iniae to assess acquired immunity. Mean cumulative mortality was significantly higher (P<0.05) in the control treatments (41.7% for the non-injected and 43.3% for the broth-injected fish) than in the low, medium and high challenge treatments (7.4%, 3.3% and 8.3% respectively). Serum protein was significantly (P<0.05) elevated in the S. iniae -survived tilapia that were subsequently challenged when compared with controls challenged for the first time. Agglutinating antibody titre was significantly higher in the fish in the medium and high challenge treatments, compared with the control fish challenged for the first time. The results suggest tilapia that survive S. iniae challenge without showing overt disease signs performed as well as non-infected tilapia. Further, the S. iniae -survived tilapia challenged following the 8-week growth performance trial gained acquired resistance to homologous S. iniae challenge. [source]

    The effects of introduced tilapias on native biodiversity

    Gabrielle C. Canonico
    Abstract 1.The common name ,tilapia' refers to a group of tropical freshwater fish in the family Cichlidae (Oreochromis, Tilapia, and Sarotherodon spp.) that are indigenous to Africa and the southwestern Middle East. Since the 1930s, tilapias have been intentionally dispersed worldwide for the biological control of aquatic weeds and insects, as baitfish for certain capture fisheries, for aquaria, and as a food fish. They have most recently been promoted as an important source of protein that could provide food security for developing countries without the environmental problems associated with terrestrial agriculture. In addition, market demand for tilapia in developed countries such as the United States is growing rapidly. 2.Tilapias are well-suited to aquaculture because they are highly prolific and tolerant to a range of environmental conditions. They have come to be known as the ,aquatic chicken' because of their potential as an affordable, high-yield source of protein that can be easily raised in a range of environments , from subsistence or ,backyard' units to intensive fish hatcheries. In some countries, particularly in Asia, nearly all of the introduced tilapias produced are consumed domestically; tilapias have contributed to basic food security for such societies. 3.This review indicates that tilapia species are highly invasive and exist under feral conditions in every nation in which they have been cultured or introduced. Thus, the authors have concluded that, despite potential or observed benefits to human society, tilapia aquaculture and open-water introductions cannot continue unchecked without further exacerbating damage to native fish species and biodiversity. Recommendations include restricting tilapia culture to carefully managed, contained ponds, although exclusion is preferred when it is feasible. Research into culture of indigenous species is also recommended. Copyright © 2005 John Wiley & Sons, Ltd. [source]

    Atrial Tachyarrhythmias Induced By Acetylcholine In Tilapia (Oreochromis SP.) Isolated Atria

    Tsai-Chu Lin
    SUMMARY 1. Effects of the parasympathetic neuromediator acetylcholine (ACh) on atrial tissues vary greatly depending on the species, the type of atrial cells and experimental conditions. The aim of the present study was to investigate, with microelectrode techniques, the arrhythmogenic effects of ACh in tilapia (Oreochromis sp.) isolated atria at room (22,25°C) and high temperature (37°C). 2. Acetylcholine (1,10 ,mol/L) shortened action potential duration (APD), depressed action potential plateau and decreased twitch force in tilapia atria, as it did in human atrial fibres. In addition, ACh induced premature responses and re-entrant tachyarrhythmias (TA; frequency range from 7 to 25 Hz) in five of 19 and 14 of 22 tilapia atria tested at room and high temperature, respectively. The higher incidence of ACh-induced TA at 37°C compared with room temperature was statistically significant. 3. The ACh-induced TA consisted of high-frequency and uniform action potentials accompanied by tension oscillation and elevation of diastolic force (flutter). Acetylcholine-induced TA could be readily abolished by atropine (1 ,mol/L) and prevented by treatment with agents with local anaesthetic properties, such as 0.1 ,mol/L tetrodotoxin or 3 ,mol/L quinidine. The antagonistic action of quinidine occurred without significant prolongation of APD. 4. The present findings suggest that pharmacological concentrations of the cholinergic muscarinic agonist ACh readily induce TA (mainly atrial flutter) in tilapia atria, presumably via sodium channel-dependent re-entrant excitation. The poikilothermic tilapia appears to be an appropriate animal model for the study of atrial TA. [source]

    Supplemental dietary flaxseed oil affects both neutral and phospholipid fatty acids in cultured tilapia

    Nilson E. de Souza
    Abstract This work aimed to evaluate the neutral lipid (NL) and phospholipid (PL) classes in tilapia (Oreochromis niloticus) muscle tissue. Tilapias were raised in captivity for a period of 5,months with increasing levels (0, 1.25, 2.50, 3.75, and 5.00%) of flaxseed oil [source of ,-linolenic acid (LNA), 18:3n -3] in substitution for sunflower oil (control). The NL/PL ratio was 1.9, and 45,fatty acids were determined for both classes of lipid. The class totals of n -3 acids always increased in all treatments, while the totals for n -6 acids always decreased (p,<0.05). For a given level of flaxseed oil, the LNA contents were consistently higher, including EPA (20:5n -3) and DHA (22:6n -3). Arachidonic acid (20:4n -6) remained high in the PL but was reduced as levels of dietary flaxseed oil were increased. The n -6/n -3 ratios decreased significantly with the rise in flaxseed oil content in all treatments, and highly unsaturated fatty acid contents increased with the levels of flaxseed oil. Overall, the influence of flaxseed oil on the fatty acid composition in the contributing NL and PL classes was to increase n -3 PUFA, thus raising the nutritional value of this freshwater fish meat and, consequently, contributing to the health of consumers. [source]

    The Effects of Dietary Yeast Culture or Short-chain Fructo-oligosaccharides on the Intestinal Autochthonous Bacterial Communities in Juvenile Hybrid Tilapia, Oreochromis niloticus,×Oreochromis aureus,

    Zhi-Gang Zhou
    The effects of dietary yeast culture (YC) or short-chain fructo-oligosaccharides (FOS) on intestinal autochthonous bacterial communities in juvenile hybrid tilapia, Oreochromis niloticus,×Oreochromis aureus, were studied by 16S rDNA denaturing gradient gel electrophoresis (DGGE). Ninety Tilapias in tanks (10 fish per tank) were randomly and equally divided into three groups. At the end of an 8-wk feeding period of CK (the control treatment), YC (3 g/kg), or FOS (1 g/kg), autochthonous gut bacteria were analyzed in intestinal samples of all fish in each tank of a recirculating aquaculture system. The clear differences in the banding patterns indicated the obvious effects of dietary prebiotics on intestinal communities in hybrid tilapia. Higher variation was detected within the dietary YC group. This difference might be due to the effects of certain immune-stimulating agents in YC on the immunity response of hybrid tilapia. It was concluded that dietary prebiotics, YC, and FOS obviously affected the intestinal bacterial community in hybrid tilapia with different patterns for different kinds. [source]

    Effect of potential probiotic bacteria on growth and survival of tilapia Oreochromis niloticus L., cultured in the laboratory under high density and suboptimum temperature

    Juan Pablo Apún-Molina
    Abstract This study examined the effect of potential probiotic bacteria on growth and survival of the tilapia Oreochromis niloticus, under high density and suboptimum temperature. Presumptive Bacillus and lactic acid bacteria (LAB) were isolated from tilapia and from their culture system and were characterized for haemolytic and enzymatic activity, and antagonism against Vibrio. Selected strains were included in the diet of juvenile tilapia and evaluated during a 134-day assay. The experiment was conducted with four treatments: (1) fish fed with commercial feed plus Dry Oil®; (2) fish fed with commercial feed plus LAB; (3) fish with bacilli in water; (4) fish with a mixture of treatments 2 and 3. Tilapias in all treatments, including bacteria, grew significantly better than fish fed with commercial feed plus Dry Oil® (control group). Survival was similar in all treatments. The physicochemical parameters of the culture system were maintained within the optimal ranges for the species, with the exception of temperature (19.9,24.82 °C). Animals fed diet supplemented with bacilli and LAB had good survival and the best growth performance, suggesting that bacteria are appropriate growth-stimulating additives in tilapia cultivation. [source]

    Multiple pathways for invasion of anurans on a Pacific island

    Michelle T. Christy
    ABSTRACT Since 1937, thirteen species of non-indigenous anurans have made their way to Guam. Of these, at least six have established breeding populations. Various pathways led to the introduction of these species to the island. The only anuran intentionally introduced was Chaunus marinus (formerly Bufo marinus), which was brought to Guam as a biocontrol agent. Kaloula picta, K. pulchra, Polypedates leucomystax, and probably Litoria fallax arrived as stowaways via maritime or air-transport vessels. Eleutherodactylus coqui and Euhyas (formerly Eleutherodactylus) planirostris appear to have entered Guam through the horticultural trade. Specimens of Pseudacris regilla were found among agricultural products and Christmas trees. Five species have been transported to Guam via the aquacultural trade. The importation of tilapia, milkfish, and white shrimp from China, Hong Kong, Taiwan, and the Philippines was associated with the introduction to Guam of Fejervarya cancrivora, F. limnocharis sensu lato, Microhyla pulchra, Polypedates megacephalus, and Sylvirana guentheri (formerly Rana guentheri). Presently, no quarantine or containment guidelines have been established for Guam's aquacultural industry. [source]