Nile Tilapia Fry Research Articles

Regulatory roles of Pawpaw (Carica papaya) seed extract on growth performance, sexual maturity, and health status with resistance against bacteria and parasites in Nile tilapia (Oreochromis niloticus)

Papaya (Carica papaya) is one of the plants that represent a major source of bioactive substances that are cheaper and non-toxic, such as antibiotics. It is globally used as a supplement diet for positive effects in pharmacological activities. In this regard, the current study sheds light on the possible roles of papaya seed methanolic extract (PSE) as a dietary supplement to improve growth performance, sexual maturity, carcass composition, immunity responses, histological structure of gonads, and anti-pathogenic activity (Aeromonas hydrophila) at the end of a feeding trial extend for ten days of Nile tilapia, with special reference to its potential effect as resistance against parasitic (Cichlidogyrus tilapiae). Four experimental groups with four replications of Nile tilapia fry (0.5 ± 0.1 g as 20 fish per replication) were fed (0, 0.5, 1.0, and 2.0 g/kg PSE in diets) for 20 weeks. Results showed that fish dietary supplementation with PSE had a significantly positive (P < 0.05) effect on growth performance, feed utilization, digestive enzyme, carcass composition, antioxidant, immunity responses, and hematological and biochemical indices, especially PSE 2.0 g/kg than control diet. Furthermore, PSE had a positively affected fish mortality after injection with A. hydrophila and in vitro positive efficacy against C. tilapiae. Fish fed with dietary PSE increased the sex ratio in favor of male fish by achieving a 77% male phenotype. Conclusively, this study declared that PSE extract, specifically 2 g/kg, could enhance growth and health through the modulation of innate immunity and a positive effect against disease in fish. Additionally, it reduced the reproductive performance of Nile tilapia by reducing GSI, which subsequently affected the gonadal histology leading to infertility.

Evaluation of an Organically Modified Clinoptilolite (OMC) and a Multi-Component Mycotoxin Detoxifying Agent (MMDA) on Survival, Growth, Feed Utilization and Disease Resistance of Nile Tilapia (Oreochromis niloticus) Fingerlings Fed with Low Aflatoxin

Mycotoxins have become a serious issue in the animal feed industry and have also affected the aquaculture industry. Mycotoxins can create serious health problems in aquatic and terrestrial animals, and their presence in agricultural products may result in significant economic losses. To reduce the impact of mycotoxins on Nile tilapia fry, two commercially available products—Organically Modified Clinoptilolite (OMC) and multi-component mycotoxin detoxifying agent (MMDA)—were used in this study. Six diets as treatments (T1 = Control (C); T2 = Control + OMC 2 g/kg (OMC); T3 = Control + MMDA 2 g/kg (MMDA); T4 = AFB1 0.5 mg/kg (AF); T5 = AFB1 0.5 mg/kg + 2 g/kg OMC (AFOMC); T6 = AFB1 0.5 mg/kg + MMDA 2 g/kg (AFMMDA)) with similar crude protein levels (35.75 ± 0.35%) were formulated and fed to Nile tilapia fry (1.97 ± 0.1 g) for a period of 84 days. These fish were housed in 18 aquaria (100 L) at a density of 50 fish/aquarium. The results from this study showed that MMDA significantly (p &lt; 0.05) improved the survival of fish by 16% as compared to the control group. Nevertheless, growth parameters were not affected among the treatments. These results also indicated that protein intake was significantly higher in the control and OMC diet (T2) compared to aflatoxin B1-fed tilapia. The protein efficiency ratio (PER) was significantly higher in the AFMMDA as compared to the control and MMDA. A 14-day bacterial challenge test with Aeromonas hydrophila demonstrated that diets containing MMDA or OMC improved survival when AFB1 was present in the diet. Therefore, the supplementation of feed with MMDA or OMC is recommended to ameliorate the negative effects of AFB1 in Nile Tilapia feeds.

Water Quality and Growth Performance of Nile Tilapia Fries Fed on Insect-Based Feeds

Fish feed is one of the main constraints on the growth of aquaculture in Kenya. The lack of high-quality and competitively priced feeds means that the fish farmers are unable to expand their production. To ensure that aquaculture remains viable and sustainable, it is necessary to optimize production through the utilization of locally available feeding materials. Insect-based feeds are alternative least-cost feeding resource in fish production. Using alternative protein sources such as black soldier fly larvae (BSF) and daphnia meal in place of fishmeal (Omena and Dagaa) is an ingenious strategy for sustainable fish aquaculture. This study evaluated the effect of four treatments: BSF, daphnia, Omena from Lake Victoria and Dagaa from Lake Tanganyika on the fish pond environmental parameters and fish fries’ performance (body weight and length). The experiment was carried out in a greenhouse with 30 fingerlings in each experimental unit. The feeding trials took 23 days. Results indicated that the four treatments have a varied effect on the BW and L of fish fries. A high growth rate was observed in Daphia, followed by BSF, Omena and Dagaa in that order. On the other hand, the treatments have varied effects on pond parameters with BSF promoting too much growth of algae. BSF have higher amounts of ammonia, nitrates and phosphorus, which stimulate the high growth of algae.

Optimization of 17α-methyltestosterone dose to produce quality mono-sex Nile tilapia Oreochromis niloticus

The 17α-methyltestosterone is the most common synthetic hormone used in male mono-sex production of Nile tilapia, Oreochromis niloticus. The current research aimed at finding out the most effective dose of 17α-methyltestosterone to produce quality Nile tilapia fry. Soon after absorbing the yolk sac, Nile tilapia fry was fed with a mixture of commercial fish feed and 17α-methyltestosterone for 28 days. Five doses of 17α-methyltestosterone, i.e., 0 mg, 50 mg, 60 mg, 70 mg, and 80 mg per kg feed, were used to treat tilapia that has been reared for additional 90 days to compare sex reversal, development, and survival rates. Both gonad histology and Squash test were performed to expose the sex percentage of O. niloticus accurately. The highest male 94.44% was obtained at 60 mg 17α-MT/kg feed dose followed by 91.67%, 88.89%, 86.11%, and 47.22% at 70, 80, 50, and 0 mg 17α-MT/kg feed dose. The groups treated with 17α-methyltestosterone hormone showed superior growth performance in comparison to the control group. The highest weight (14.62 ± 0.59 g) and length (92.18 ± 3.01 mm) were found at 60 mg dose whereas the lowest weight (8.64 ± 0.38 g) and length (70.17 ± 3.75 mm) were in the control group. The group given 60 mg 17α-MT feed represented the highest survival rate (84.10%) among other hormone-treated groups. The study disclosed that 60 mg 17α-MT/kg feed might be treated as the optimal dose for producing quality mono-sex male tilapia in the commercial hatchery.

Impact of orange (Citrus sinensis) peel meal as feed additive in the diets for mono-sex Nile tilapia (Oreochromis niloticus) fries

Impact of orange (Citrus sinensis) peel meal as feed additive in the diets for mono-sex Nile tilapia (Oreochromis niloticus) fries

Sex reversal dynamics of Nile Tilapia (Oreochromis niloticus) and impact on growth performance

AbstractNile Tilapia (Oreochromis niloticus) is one of the most economically important freshwater aquaculture species globally. However, reproduction during grow-out is a major problem that hinders fish growth. Therefore, production of all-male populations of tilapia has been developed to address the problem and is also identified as one of the most effective techniques of increasing tilapia growth. Various methods have been used to produce all males in Nile Tilapia i.e. use of hormone treatment (17- α-methyltestosterone), use of temperature shock and the recent YY technology. The latter two methods have limited documentation and usage in Kenya. The current study compared effectiveness of temperature and hormone sex reversed O. niloticus fry and influence on growth in hapa nets over a period of 3 months. Nile Tilapia fry of 3 days old after egg yolk absorption were sex reversed using hormone for 21 days and temperature shock for a period of 14 days. Hormone use involved making a dose of 60 mg kg-1 of feed while temperature shock involved raising temperature from 28°C to between 30 °C and 34 °C. Analysis of Specific Growth Rate using one-way analysis of variance, ANOVA, showed no significant difference between hormone and temperature induced sex reversed fish (F = 0.0975, P = 0.7705). Sex reversal efficacy rates of 91.18% and 92.86% were attained using 17- α-methyltestosterone hormone and temperature shock, respectively. The results indicate that temperature shock could be a replacement for Tilapia sex reversal without any negative consequences on growth.

The positive impact of partial substitution of fish meal by a meal mixture of duckweed and mealworm larvae on the diets of Nile tilapia fry (Oreochromis niloticus Linnaeus, 1758)

In ordre to promote aquaculture in the south of the country, and specifically, to reduce the cost of feeding farmed fish, this study was carried out to evaluate the effect of partial replacement of fishmeal with a mixture of duckweed meal (DWM) and mealworm larvae (WLM) on growth performance, feed utilization and carcass composition of Nile tilapia. Eight-week feeding experiment was conducted on fry of O. niloticus (average initial weight: 0.87 ± 0.23 g). Four isoproteic diets (38.52 ± 0.11% crude protein) comprising control diet D0 and three test diets (D1 to D3) were formulated and tested in triplicates. To satisfy EAA requirements in test diets, the ratios 1: 5; 2: 4 ; 4: 2 between DWM and WLM were used respectively in partial replacement for fishmeal. No significant differences (P &gt; 0.05) were observed in survival, growth and feed utilization. On the other hand, the compositions of the carcasses showed strong significant differences (P &lt; 0.05) except ash contents. The carcass lipid increased proportionally with the inclusion of WLM, but the reverse was true for the moisture content. However, the high contents of retained proteins were obtained in the ratios 0 : 0 and 4 : 2 between D0 and D3. It is concluded that fishmeal could be replaced by a meal mixture of DWM and WLM up to the proportion (4 : 2, respectively) in the feed of O. niloticus without adverse effects on growth and nutrient utilization and most importantly, reduce the cost of production up to 29.8% which would have a positive impact on post-feeding and therefore the financial management of an aquaculture farm.

The Effects of Substituting Fishmeal Based-Diet With Plant Based-Diet on Nile Tilapia (Oreochromis niloticus) Fish Growth, Feed Efficiency and Production Cost-Effectiveness

Aquaculture started in The Gambia in 1979 but is still at a rudimentary stage. Many government and private interventions conducted on fish farming failed due to the high cost of feed. Fishmeal based diets are expensive thus using them makes many fish farming in the developing countries unprofitable businesses. There is a need to use locally available plant ingredients to develop fish feeds. This study was conducted to compare the growth, feed efficiency and production cost-effectiveness of the Nile tilapia (Oreochromis niloticus) fish fed on fishmeal-based diet (control diet) to that of the same fish fed on plant-based diet (test diet). The two isonitrogenous (30 % CP) experimental diets were tested on 0.81g Nile tilapia (Oreochromis niloticus) fry for a period of six (6) weeks. The control diet composed of fishmeal, soybean meal, cassava flour, and a blend of palm oil and fish oil premixed with mineral and vitamin supplements. The plant-based diet consisted of groundnut cake, wheat flour, brewery waste and rice bran supplemented with mineral and vitamin premixes. Regarding growth performance parameters, there were significant differences between the final mean weight, mean weight gain, percentage mean weight gain and the specific growth rate of Nile tilapia (Oreochromis niloticus) fish fed on the control diet and the plant-based diet. For feed efficiency parameters, there was significant difference between feed conversion ratio for fish fed the control diet and the plant-based diet. However, there was no difference between the fish fed the two diets with regards to the protein efficiency ratio or survival rate. The plant-based diet was inferior to the fishmeal-based diet in terms of growth and feed efficiency parameters of 0.81g Nile tilapia (Oreochromis niloticus) fry. When compared to the fish-meal based diet, the plant based-diet was more cost-effective in producing a kilogram of feed but less cost-effective in producing of a kilogram of fish. Therefore, a plant based-diet cannot replace a fishmeal based-diet without compromising Nile tilapia (Oreochromis niloticus) fish growth performance and production cost-effectiveness.

Black soldier fly (Hermetia illucens, L.) larvae meal improves growth performance, feed efficiency and economic returns of Nile tilapia (Oreochromis niloticus, L.) fry

AbstractInsects have been proposed as potential alternative animal protein sources to replace fishmeal (FM), which is expensive and has limited availability for fish feed formulation. However, studies on the effects of replacing FM with black soldier fly (Hermetia illucens) larvae (BSF‐L) on growth performance of Nile tilapia (Oreochromis niloticus) fry, water quality and economic benefits are currently limited. This study determined the effects of replacing 100% FM, 75% FM, 50% FM, 25% FM and 0% FM with cheap BSF‐L meal, hereafter referred to as BSF‐L0, BSF‐L25, BSF‐L50, BSF‐L75 and BSF‐L100 diets, respectively for rearing all‐male Nile tilapia fry produced by YY technology. The study further determined the optimum percentage of BSF‐L meal for maximum growth of Nile tilapia fry. A total of 2400 visually healthy Nile tilapia fry weighing 0.001 g were randomly stocked into 20 plastic tanks (120 fry per tank, four replicates per treatment) and fed the BSF‐L diets for 12 weeks. The BSF‐L75 diet increased significantly specific growth rate, total weight gain, Zihler's index of fry and nitrate in the culture water but reduced feed conversion ratio of diet and total suspended solids in the culture water (p &lt; 0.05). Feeding the Nile tilapia fry with BSF‐L50 diet increased significantly hepatosomatic index (p &lt; 0.05). The diets with BSF‐L75 and BSF‐L100 reduced significantly the incidence cost by 31.97% and 28.77% (p &lt; 0.05), and increased profit index by 3.97 and 3.44%, respectively. The optimum percentage of BSF‐L inclusion required for maximum growth performance of Nile tilapia fry was estimated as 81% to 84% based on polynomial analysis. Taken together, feeding Nile tilapia fry with diets containing 81% to 84% BSF‐L meal improved growth performance. The BSF‐L75 diet enhanced feed efficiency and had no deleterious effect on the liver and intestines. Meanwhile, it improved nitrate concentration for increased natural productivity. Incorporating 75% BSF‐L meal in diets for Nile tilapia fry reduced 30% of feed cost leading to 4% higher economic returns.

Effect of Biotronic® Top Liquid Supplementation on the Growth Performance and Disease Resistance of Nile Tilapia (Oreochromis niloticus L.)

The present trial was conducted to evaluate whether Biotronic® Top Liquid (BTL) supplementation would benefit during the nursing of Nile tilapia (Oreochromis niloticus) fry in terms of survival, growth, and disease resistance. Isonitrogenous (22.9±0.2% CP) diets were prepared by supplementing 0.0, 0.5, 1.0, 1.5, 2.0 to 2.5 L/ton of BTL diet i.e. T1 to T6, respectively. Each of the 18 aquaria (100 L) was stocked with 45 fish (16.17±0.40g, Mean±SE) having three replicates per treatment. During the trial, fish biomass increased linearly with the increase in BTL dose i.e. 230g (10.3%) of fish biomass/L of BTL. Results showed that higher dose of BTL/ton of feed resulted in to increase growth rate, with an indication of improved growth beyond the tested level i.e. &gt;2.5 L/ton. Bacterial challenge test using Aeromonas hydrophila showed that the highest BTL dose could maintain average fish survival rate above 65%, which was 25% higher than that of control. Average survival improved linearly i.e. (y)=8.857x+40.317 (R²=0.64) with a nearly 9% increase in survival per liter of BTL supplementation. BTL improved SGR, DWG, and PER by 3.4, 1.6 and 2.1 times, respectively as compared to the control when the fish were challenged by bacteria. Therefore, the dose of 2.5 L/ton of feed is recommended based on the present study.

Repercussion of salinity on hematological parameters and tissue morphology of gill and kidney at early life of tilapia

This study was attempted to reveal the changes in three hematological parameters such as blood hemoglobin, number of white blood cells (WBCs) and number of red blood cells (RBCs) and one biochemical (e.g., glucose) parameter along with the changes in histomorphological structures of gills and kidney of Nile tilapia fry reared in saline water. Two experimental set up were used for two different age groups- 5 days-after-hatch (5DAH) and 15 days-after-hatch (15DAH) - to test a novel hypothesis: if a little difference in the age during the first exposure to saline water could produce any variation in the results. They were placed into 6 plastic drums having six different salinity levels: 0, 5, 10, 15, 20 and 25. After 60 days, at least 5 individuals were taken out from each drum to observe the above-hematological and histomorphological parameters. A two-way-ANOVA revealed that, except for hemoglobin, all the observed parameters have been affected the effect of age × salinity interaction (P<0.05). Between the two age groups, only the overall average glucose value and RBC count were significantly different. Among various salinity levels, only RBC and WBC counts differed significantly. Further, the mean glucose value, RBC counts and WBC count at different salinities differed significantly from the base mean value of each parameter. With regard to the histomorphological structure of the gills and kidney, various malformations were evident. Though hypertrophy, epithelial uplifting and epithelial necrosis were present as gill degenerations, hyperplasia was prevalent across almost all salinity levels. On the other hand, glomerular necrosis, pyknotic nucleus, hyaline droplets degeneration, shrinking of the glomeruli, etc. were observed in kidney structures. By assisting to understand the effects of salinity stress, all these data on tilapia fry will help to determine the prospects and scope of culturing the species in high-salinity water.

Histopathological changes and tissue residue concentrations of monosex Nile tilapia (Oreochromis niloticus, L) fries exposed to oxytetracycline.

The current study evaluated the biosafety of oxytetracycline (OTC) exposure for 30 days in monosex Oreochromis niloticus fries. The fries were exposed to OTC for 3 h/day for 30 days at 350 (0.5X), 700 (1X), 2100 (3X), 3500 (5X), and 7000 (10X) mg/L and compared with control (0X). The OTC exposure at 5X and 10X concentrations caused 100% mortality within 4 days and 5 min, respectively. The mortalities recorded in 0.5X, 1X, and 3X groups were 3.33 ± 1.15%, 14.67 ± 1.15%, and 47.33 ± 11.37% on day 30, respectively. The feed intake was decreased up to 23.33% in the 3X group during the exposure period. The OTC residue levels on 30-day exposure were 216.53 ± 14.71, 450.56 ± 44.31, and 1141.26 ± 63.64 μg/kg, which reduced to 40.40 ± 3.25, 76.68 ± 2.77, and 95.61 ± 5.13 μg/kg after 15 days of termination of exposure in the 0.5X, 1X, and 3X groups, respectively. The histopathological changes observed in the 1X group were epithelial detachment, desquamation of secondary lamellar epithelium, lamellar fusion, and inflamed cartilaginous core in the gills, alteration in the integrity of gut mucosa, degeneration of muscularis mucosae and necrosis in the intestine, the disintegration of the nephritic tubule, necrosis, and glomerulopathy in the kidney, and dilated vascular duct, necrotized hepatic tissue, diffused hepatic parenchyma, vacuolation, and fatty changes in the liver. The OTC exposure induced marked tissue changes histologically in a dose- and time-dependent manner, which undoubtedly reduced the growth of tilapia.Supplementary InformationThe online version contains supplementary material available at 10.1007/s10499-022-00892-w.

Mixed-sex Nile tilapia (Oreochromis niloticus) can perform competitively with mono-sex stocks in cage production

All-male tilapia stocks are widely used by farmers to supply both domestic and international markets with homogenous, large sized fish (500 g+). While a number of strategies are possible, hormonal treatment of fry with 17α-methyltestosterone (MT) is the most common method used by commercial farmers due to its low cost and ease of application. However, contrasting to its current widespread use, the implications of MT in tilapia farming have raised concerns especially from public and environmental perspectives. Therefore, in this study we tested the impact of stocking a mixed-sex fast growing strain of Nile tilapia (Oreochromis niloticus) fry at high density and then grading out females at 4 or 8 weeks intervals during grow-out and compared final production with a standard MT-treated mono-sex system. From a production perspective, the strategies to remove females at 4 or 8 weeks were successful as no differences in harvest weight, survival and feed conversion rate were observed when compared to the MT-treated group. Similarly, no differences at harvest were obtained in terms of external appearance, Fulton's condition factor, gonadosomatic index, fillet yield, fat-somatic index and visceral-somatic index (%) between MT-monosex group and the groups where females were removed (4 or 8 weeks). However, a financial analysis of this approach showed that the additional costs (fry, feed and labour) involved in the mixed-sex strategy resulted in lower profits. This could be mitigated if a proportion of the removed females could be sold at a premium price as potential broodstock. In the model presented, sales of 13% of the removed females for broodfish at current Thai prices, or a premium of at least 8% for non-sex-reversed final product would be sufficient for the mixed-sex system to return a higher profit than the mono-sex system. The latter strategy could also enable further social licence through use of small fish in nutritional and outgrower initiatives.

Hematobiochemical and histopathological alterations in Nile Tilapia (Oreochromis niloticus) exposed to ethidium bromide: The protective role of Spirulinaplatensis

Ethidium bromide (EtBr) is one of the contaminants recorded in aquatic environments whose effects have been investigated; however, there is still limited knowledge about its remediation. This study examined the potential protective effects of Spirulina platensis (SP) against the effects of EtBr toxicity in the Nile tilapia (Oreochromis niloticus) fry. Fry were divided to five groups, viz., a control and four treatment groups of low-dose EtBr (10 μg/L), low-dose EtBr with SP (10 μg/L EtBr + 200 mg/L SP), high-dose EtBr (100 μg/L), and high-dose EtBr with SP (100 μg/L EtBr + 200 mg/L SP); the exposure period was 2 weeks. Low and high doses of EtBr induced alterations in some hematological, biochemical, and histopathological parameters. Necrotic hepatocytes, degenerated area, vacuolated hepatocytes, pyknotic nuclei, constricted and dilated blood sinusoids, and infiltration of inflammatory cells were observed. Lipid peroxidation concentration was not significantly different in groups exposed to low doses of EtBr and EtBr with SP, but it was increased in groups exposed to high doses of EtBr and EtBr with SP, compared with the control group. After feeding with SP, most histological and histochemical parameters restored to normal values. Therefore, SP may possess the ability to preserve the structural integrity of the hepatic and renal membranes.

Pterygoplichthys spp. (Siluriformes: Loricariidae) meal is suitable for the culture of Nile tilapia Oreochromis niloticus (Cichlidae) juveniles

ABSTRACT: We search for positive utility impact on the invasive species Pterygoplichthys spp. The optimal level of replacement of sardine meal (SM) by Pterygoplichthys spp. meal (PLM) in practical feeds for fry of Nile tilapia (Oreochromis niloticus) was evaluated. We evaluated six experimental diets: 50% PLM-50% SM, 60% PLM-40% SM, 70% PLM-30% SM, 80% PLM-20% SM, 90% PLM-10% SM and 100% PLM-0% SM. In a recirculation system, 270 sex-reversed tilapia fry were used (0.7 ± 0.1 g). Diets were administered in triplicate and the experiment lasted 56 days with sampling every 14 days. There were no statistical differences in growth. At the end of the experiment, the SGR, ADG, CF, WG, DFI, FCR and PER were determined without significant differences (P &gt; 0.05) between treatments, but there was a tendency that could indicated higher WG and PER in the 90% PLM-10% SM treatment (93.56 ± 0.43% and 8.44 ± 1.18 g, respectively). All survival rates were higher than 90% with no significant differences. Additionally, there were no statistical differences in the chemical composition of the whole fish, while apparent digestibility coefficients of protein (81-90%) and lipids (87-93%) also showed no significant differences. We concluded that 100% PLM can replace 100% SM in feeding fry of O. niloticus without affecting their survival, growth or chemical composition or the apparent digestibility of nutrients.

Suitable Temperature, Stocking Density and Feeding Rate for Optimal Growth of Sex Reversed Fry of Nile Tilapia &amp;lt;i&amp;gt;Oreochromis niloticus&amp;lt;/i&amp;gt; (Senegal River Strain)

Determining the suitable fish farming conditions for optimal growth is necessary for aquaculture production, but it is not very obvious because it requires a good understanding of species biology. Thus, this study aims to evaluate the effects of different temperature regimes, stocking densities, and feeding rates on the growth of Nile tilapia, Oreochromis niloticus fingerlings that have been sex-reversed with 17α methyl testosterone. Three independent experiments were performed (with replicates) at the IRD Bel-Air fish farm (Dakar, Senegal) on 27-day-old fry maintained in six 25 L tanks with a batch of 100 individuals each. These fry were subjected to three different temperatures (26˚C, 28˚C, 30˚C; kept constant with thermostats), stocking densities (5, 10 and 15 ind/l) and feeding rates (5%, 10% and 15% of biomass; distributed three times a day). For the temperature and density treatments, fry was fed a pelleted feed containing 38% protein, distributed by hand at 10% of their total biomass, readjusted after each measurement. Growth performance (total weight, weight gain and daily weight gain), physicochemical parameters (temperature, oxygen, nitrite and phosphorus), feed conversion ratio (FCR) and survival rate (SR) were regularly monitored (weekly) during the experimental period. For the heat treatment, the results did not show an apparent relationship between growth performance and nitrite, phosphorus or dissolved oxygen (DO) contents. In contrast, there was a significant correlation between temperature and growth rates, with the best growth being obtained at 30˚C compared to 28˚C and 26˚C. Similarly, growth rates were correlated with stocking density and feeding rate but not with oxygen, temperature, nitrite or phosphorus levels. The best growth rates were observed at the lowest density (5 ind/l) and for the highest feeding rate (15% of biomass), which coincides with the best FCR and survival rates. Thus, 30˚C, 5 ind/l and 15% of biomass appeared to be the most favorable temperature, stocking density and feeding rate for optimal growth of Nile tilapia fry after inversion. The application of these results in the culture systems will allow to reach a good production of O. niloticus and thus to contribute to sustainable development of fish culture in Senegal.

Substitution of Fish Meal with Shea Nut Meal in Diets of Nile Tilapia Fry on Growth, Feed Utilization, Tissue Histology and Economic Analysis

Substitution of Fish Meal with Shea Nut Meal in Diets of Nile Tilapia Fry on Growth, Feed Utilization, Tissue Histology and Economic Analysis

Histological changes in the gills, livers and muscles of Oreochromis niloticus fed with steriod, natural hormone and pawpaw seed based diets

This study was conducted to evaluate the histological changes of 17αmethyl-testosterone (MT), wet testes of bull (Bos indicus), boar (Sus domesticus), bull/mud catfish testes (B. indicus/C. gariepinus) and pawpaw (Carica papaya) seed powder-based diet on the Nile tilapia fry in an indoor experimental pond. Histological changes and efficacies in producing monosex males were determined after four months. Fifty-five fry were assigned randomly to three experimental ponds in triplicates. Five experimental feeds composed of soya-bean, fish meal, wheat bran, cassava flour were formulated by adding 0.06g of 17α- methyl-testosterone, 17.47g of bull wet testes, 25.59g of boar wet testes, 20.48g of bull/catfish and 20g of pawpaw seed powder per kg of feed to group 1, 2, 3, 4, 5 respectively. Obtained results from the morphological examination revealed a significant difference (p &lt; 0.05) in phenotypic males of the Nile tilapia fry fed with the experimental diets. The highest indistinct percentage was recorded in the 17αmethyl-testosterone-treated diet while the lowest was recorded in diets 3 and 4 with no significant differences. All the groups showed histopathological differences in the livers, gills, and muscles. However, the liver histology of groups 1 and 5 showed central vessels that are mildly congested with abundant glycogen vacuolation and somewhat fat infiltration, while the histology of the muscles of group 5 showed pathological lesions including moderate to severe necrosis. These alterations can be considered an indication of the performance and health of fish in monosex culture medium indicating effects of plant extract and MT.

Influence of Water Temperature and Salinity on Rearing of Nile Tilapia Fry under Biofloc Culture System

Influence of Water Temperature and Salinity on Rearing of Nile Tilapia Fry under Biofloc Culture System

Utilization of fish waste as fish meal substitute in formulated fish diet on the growth performance of Nile tilapia fish fry (Oreochromis niloticus)

Fish meal is generally expended as the foremost protein supply in the fish diet. The rising cost of this component inflicted the aquaculture industry to seek a substitute in lessening the pellet cost. Thus, fish waste was tested in this study to investigate its viability. An experiment was performed to study the effects of fish waste and carcass on the growth performance of Nile tilapia fry. Solid fish waste of three different common species available in Mukah’s wet market was formulated into an artificial diet. The diet was formulated into three treatments consist of three protein levels (40%, 45% and 50%) with 4000 kcal/kg energy. A controlled group was fed with a commercial pellet consisting of 45% protein level. Fish were fed at 4% of body weight twice daily for 45 days. Fry reared in a controlled group was discovered highest weight gain, specific growth rate and length gain. There was no significant difference in all treatments for all parameters measured. The lowest weight gain and specific growth rate were recorded in fish fed 45% protein level (T2) group. Fish in T3 (50%) achieved the highest survival rate while T1 (40%) group recorded the lowest. The best and lowest Feed Conversion ratio (FCR) was recorded in the control group. In conclusion, the performance of formulated feed using fish waste is similar to commercial pellet as no significant difference can be observed in all parameters measured.