Niloticus Juveniles Research Articles

The effects of extended feeding of florfenicol coated medicated diets on the safety, serum biomarkers and blood cells morphology of Nile tilapia Oreochromis niloticus (L.).

Tilapia is one of the most consumed farmed fish, which requires the use of antibiotics in certain phases of its production. This study assessed the safety of 30days of oral florfenicol (FFC) dosing at 0-10 times the therapeutic dose (1 × : 10mg/kg biomass/day) in Oreochromis niloticus juveniles. Behavioural changes, feed consumption, mortality and biomass were evaluated. Besides, the levels of serum glucose, calcium, chloride, creatinine, alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase and blood cell morphology were determined at scheduled intervals. The 30days of oral FFC dosing caused 3.33% (1 ×) to 18.33% (10 ×) mortalities, reduced feed intake and biomass in a dose-dependent manner. The fish fed the therapeutic dose recorded 1.25-fold increase in biomass, while the control group recorded 1.45-fold increase in 30days. No significant erythrocyte morphological alterations were observed in the 1 × group compared to the control. However, marked morphological alterations like tear-shaped, spindle-shaped and degenerative erythrocytes in higher dosing groups indicated FFC cytotoxicity. All the serum biomarkers of O. niloticus increased significantly on day 10 and day 30 FFC dosing in a dose-dependent manner, except for calcium and chloride, which reduced significantly during the dosing period. Within 2weeks of suspension of FFC dosing, the serum biomarker levels became normal except for alkaline phosphatase and creatinine. The recovery of biomass, feed intake, serum biomarker levels and erythrocyte morphological changes suggested that the FFC-induced changes are reversible. This study has, thus, proclaimed the safety of FFC at the therapeutic dose in O. niloticus.

Black soldier fly (Hermetia illucens) larvae meal improves growth performance, feed utilization, amino acids profile, and economic benefits of Nile tilapia (Oreochromis niloticus, L.)

This study investigated the effect of replacing soybean meal (SBM) with black soldier fly larvae meal (BSFLM) on the growth performance, feed utilization, carcass body composition, and amino acids profile of Nile tilapia (Oreochromis niloticus). Three isonitrogenous (30% crude protein) diets containing BSFLM in varying proportions of 0% (BSFLM0), 50% (BSFLM50), and 100% (BSFLM100), were formulated to replace SBM. A commercial diet (COMM0) sourced from the local market was used as a positive control. Male sex-reversed O. niloticus juveniles of a mean weight 20.88 ±0.16 g were stocked in 12 cages each at a density of 12.5 fish m-3. Fish were hand-fed at 5% (28 days), 3% (54 days), and 2.5% (84 days) of the body weight twice a day (1000 hrs and 1600 hrs). Significant differences (P < 0.05) were found in the final body weight, body weight gain (BWG), specific growth rate (SGR), feed conversion ratio (FCR), survival rate, and condition factor (K). The best growth performance and feed utilization was recorded in fish fed on BSFLM100. The different diets had significant effects on the body composition and amino acid profiles of the experimental fish (P<0.05). Fish fed on BSFLM100 exhibited highest values for phenylalanine, threonine, Isoleucine, lysine, proline, and glutamic acid amino acids. The partial enterprise budget analysis indicated that replacing SBM with BSFLM at 50% and 100% reduced the cost of production compared to the control diet (BSFLM0) and commercial diet (COMM0). The study demonstrated that BSFLM is a cost-effective alternative to SBM in the diets of Oreochromis niloticus hence can replace soybean meal up to 100% without negative effect on growth and carcass body composition.

Periphyton Technology Enhances Growth Performance and Delays Prolific Breeding of Nile Tilapia, Oreochromis niloticus (Linnaeus, 1758), Juveniles

This study evaluated the effect of periphyton technology (PPT) on the growth performance and breeding schedule of Oreochromis niloticus (Linnaeus, 1758) juveniles. Six ponds, each measuring 81 m2 were used for the study. The ponds were applied with agricultural lime at a rate of 4 g.m-2, and fertilised using chicken manure to facilitate primary productivity. The PPT ponds were fitted with two-metre-long eucalyptus poles of 5 cm diameter placed at 50 cm intervals with the regular addition of molasses as a carbon source. Tilapia juveniles were stocked at a density of 3 fish.m-2 in all ponds and fed on a commercial diet of 20 % crude protein (CP) twice daily at 3 % body weight. Fish were sampled weekly for growth and survival data and bi-weekly for fecundity estimates. The PPT-ponds registered significantly higher survival rate (97.50 ± 0.35 %), mean weight (150.69 ± 0.99 g), specific growth rate (SGR) (2.75 ± 0.01), and feed conversion ratio (FCR) (1.29 ± 0.01), than the control ponds, which registered survival (91.15 ± 0.88 %), mean weight (99.23 ± 0.96 g), SGR (2.29 ± 0.00), and FCR (1.58 ± 0.01). There was significantly higher fecundity in the PPT-ponds (2.28 ± 0.09 g.fish-1) than control (1.74 ± 0.06 g.fish-1), with prolific spawning starting 4 weeks earlier in the control ponds than in the PPT-ponds. This study demonstrated the potential of PPT for enhancing tilapia growth while delaying prolific breeding behaviour. Further studies should explore PPT in replacing synthetic hormones for sex-reversal of tilapia fry in hatcheries.

Assessment of temperature effects on body shape in Nile tilapia, Oreochromis niloticus juveniles using the truss network system

Among the environmental factors, water temperature has a significant effect on many aspects of fish life. This study was carried out to examine effects of water temperature on body shape of Nile tilapia, Oreochromis niloticus during the early stages of life using truss network system. A total of 150 newly-born fry were reared in three temperature treatments (22, 28 and 34°C) for 40 days. At the end of experiment, the left side of the specimens was photographed. To achieve the body shape data, 13 landmark-points were digitized using tpsDig2 software. The extracted data were justified with generalized procrustes analysis, then the differences of body shape among groups were investigated using the principal component analysis (PCA), canonical variate analysis (CVA) and cluster analysis (CA). There were significant differences in body shape of the treatments. The results of CVA and CA indicated that one of the important factors in the aquatic habitats is water temperature that influences the body shape of the Nile tilapia during the first stages (larval and juvenile stages) of growth.

Sublethal behavioral and biochemical toxicity of cypermethrin in juvenile Oreochromis niloticus in a static bioassay

Abstract Sublethal behavioral and biochemical toxicity of cypermethrin in Oreochromis niloticus (L.) juveniles was accessed under static conditions at concentrations of 0.5, 1.1, and 2.1 µg L−1 for up to eight weeks. The juveniles were highly sensitive to cypermethrin, with a 96-h LC50 of 12 µg L−1. Biphasic trends were noted for four avoidance behaviors: loss of equilibrium; erratic swimming; air gulping; opercular ventilation. Dose- and duration-dependent increases occurred in mucus secretion and color change. Mixed trends were noted for mean glutamate pyruvate transaminase, triglycerides, proteins, and cholesterol. These parameters decreased significantly depending on dose and duration in weeks two and six, but they increased in week eight. Mean glucose and glutamic oxaloacetic transaminase increased significantly depending on dose and duration up to week eight. No differences in glucose were noted in the control in week two. The findings of the present study confirmed that cypermethin adversely affected the health of fish even at a sublethal level.

RETRACTED ARTICLE: The role of ascorbic acid combined exposure on Imidacloprid-induced oxidative stress and genotoxicity in Nile tilapia

Imidacloprid (Imid), a systemic neonicotinoid insecticide, is broadly used worldwide. It is reported to contaminate aquatic systems. This study was proposed to evaluate oxidative stress and genotoxicity of Imid on Nile tilapia (Oreochromis niloticus) and the protective effect of ascorbic acid (Asc). O. niloticus juveniles (30.4 ± 9.3 g, 11.9 ± 1.3 cm) were divided into six groups (n = 10/replicate). For 21 days, two groups were exposed to sub-lethal concentrations of Imid (8.75 ppm, 1/20 of 72 h-LC50 and 17.5 ppm, 1/10 of 72 h-LC50); other two groups were exposed to Asc (50 ppm) in combination with Imid (8.75 and 17.5 ppm); one group was exposed to Asc (50 ppm) in addition to a group of unexposed fish which served as controls. Oxidative stress was assessed in the liver where the level of enzymatic activities including superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPX) in addition to mRNA transcripts and, Lipid peroxidation (LPO) were evaluated. Moreover, mitotic index (MI) and comet assay were performed, in addition, the erythrocytic micronucleus (MN), and nuclear abnormalities (NA) were observed to assess genotoxicity in fish. Imid exposure induced significant (p ˂ 0.05) changes in the antioxidant profile of the juveniles' liver by increasing the activities and gene expression of SOD, CAT and GPX as well as elevating the levels of LPO. DNA strand breaks in gill cells, erythrocytes and hepatocytes along with erythrocytic MN and NA were also significantly elevated in Imid-exposed groups. MI showed a significant (p ˂ 0.05) decrease associated with Imid exposure. Asc administration induced a significant amelioration towards the Imid toxicity (8.75 and 17.5 ppm). A significant protective potency against the genotoxic effects of Imid was evidenced in Asc co-treated groups. Collectively, results highlight the importance of Asc as a protective agent against Imid-induced oxidative stress and genotoxicity in O. niloticus juveniles.

Efficiency of fatty acid-enriched dipteran-based meal on husbandry, digestive activity and immunological responses of Nile tilapia Oreochromis niloticus juveniles

This study aimed to compare the enrichment capacity of polyunsaturated fatty acids (PUFA) and the long chain polyunsaturated fatty acids (LC-PUFA) of two dipteran species, Hermetia illucens - black soldier fly (BSF) - and a blowfly, Chrysomya putoria (CP), and to test its influence on growth, digestive activities and immune responses of Nile tilapia. Two types of enriched insect larval meal were produced using larvae cultured either on vegetable substrates (VGS) to formulate two diets rich in linolenic acid (ALA) (BSF/VGD and CP/VGD), or on fish offal substrates (FOS), in order to produce two diets rich in ALA and eicosapentaenoic acid (EPA) (BSF/FOD) or in ALA + EPA and docosahexaenoic acid (DHA) (CP/FOD). These four insect-based diets containing only palm oil as a lipid source were compared to a control diet based on fish meal (FM) and fish oil (FO). After 60 days of feeding, ALA or DHA muscle content of fish fed BSF/VGD or CP/FOD diet was comparable to that of the FMFO diet, and all insect diets increased the EPA muscle levels, except for a reduction by the BSF/VGD one. The CP/FOD diet induced similar fish growth, feed efficiency and protein efficiency ratio compared to the control FMFO diet, while a decrease was observed in fish fed other insect diets. Only BSF/VGD led to a decrease in protein and lipid digestibility. CP or BSF larval meal significantly increased alkaline phosphatase activity regardless of fatty acid (FA) enrichment. The expression level of fads2, fads6 and elovl5 was significantly higher in fish fed the BSF/VGD diet compared to fish fed the FMFO diet. FA-enriched insect diets increased some immune variables such as lysozyme, peroxidase and ACH50 values of fish fed CP/FOD, CP/VGD or BSF/VGD diets. Moreover, the expression level of β-defensin-1 and mhcII genes were significantly higher in fish fed the BSF/FOD diet than the FMFO diet. Also, the expression of the pro-inflammatory gene il-1-β was significantly higher in fish fed FMFO diet than in those fed CP/FOD diet, but comparable to fish fed all other diets. No significant effects were observed for the other tested genes. The results showed a better efficiency in LC-PUFA enrichment of the CP larvae compared to BSF ones, resulting in a higher stimulation of the fish nutrient utilization processes and therefore, a higher growth capacity. Nonetheless, all dipteran larval meal stimulated the immune status whatever the insect species or dietary essential fatty acids.

Accumulation and clearance of tissue residues and health status of Nile tilapia Oreochromis niloticus (L.) juveniles as influenced by the extended oral oxytetracycline-dosing

Antibiotics are considered an important primary therapy for bacterial diseases in aquaculture. This study evaluated the influence of oral administration of oxytetracycline (OTC) on feed intake, growth, mortality, residue accumulation and clearance, and histopathological changes in the vital organs of six groups of Nile tilapia Oreochromis niloticus when fed at 0-10 times the therapeutic dose (1×: 80 mg/kg biomass/day) for 10 and 20 consecutive days. The feed intake was reduced only slightly, viz., 2% in 10-day and 4.25% in 20-day dosing trials at 1× dose compared to control. While in other groups, an OTC-dose-dependent reduction in feed intake up to 31.25% was noted. The fish of the 0.5× and 1× groups recorded significantly high biomass, while the other OTC-dosed groups recorded significantly lower biomass than the control. The fold change in biomass between the control and 1× groups was insignificant. Dose-dependent mortalities were recorded in OTC-dosed fish in 10-day (1.67-6.67%) and 20-day (3.33-8.33%) trials. The OTC concentration in fish muscle established a dose- and time-response relationship. The OTC residue levels in muscle even on day 20 OTC-dosing were lower than the maximum residue limit (MRL) permitted by Codex Alimentarius (200 ng/g). On day 23 post OTC-dosing, the residue levels were traces to <10 μg/g in all groups, except the 10× group. The OTC-dosing caused mild to moderate pathological changes in the gills, liver and kidney of O. niloticus and the fish were able to mount adaptive biological responses to overcome the stress with time.

Acute toxicity of Jatropha curcas (barbados nut) latex extracts to Oreochromis niloticus juveniles

The effects of the latex extract of Jatropha curcas on mortality rate, opercular ventilation rate and some behavioural responses of Oreochromis niloticus juveniles were investigated under laboratory conditions over a 96 hours exposure period. Juveniles of Oreochromis niloticus (Trewavas) were exposed in plastic aquaria to 0.00mg.l-1 (control), 10mg.l-1, 15mg.l-1, 20mg.l-1, 25mg.l-1 and 30mg.l-1. Their opercular beats per minute, tail fin beats per minute, mortality and probit kill were determined. Symptoms of toxicosis observed include agitated swimming, loss of equilibrium, air gulping, periods of quiescence and death. Within 24 hours the opercular ventilation beats and tail fin beats of the exposed fish were significantly higher than in control fish (p&lt;0.05). At 72 hours and 96 hours the opercular and tailfin beats in the control fish were significantly higher (P&lt;0.05) than the exposed fish. The 96 hours LC50 was determined as 5.23 ml/l. Include significance of this study to conclude abstract.&#x0D; Key words: acute toxicity, Jatropha curcas latex extract, Oreochromis niloticus, haematological parameters.

Performance of Oreochromis niloticus juveniles fed autoclaved mango seed kernel diets

Human and livestock population increase has led to escalating prices of energy feed stuffs used in aquaculture. There have been some researches on various inexpensive agro-industrial by-products as substitutes for maize in fish diets with varying degrees of success. This study investigated the growth performance of Oreochromis niloticus juveniles fed with autoclaved Mango seed formulated fish diet as a dietary energy source at different inclusion level. 150 Oreochromis niloticus juveniles with mean weight of 10.24±0.05g were randomly allocated to five dietary treatments (T1, T2, T3, T4, T5). The fish were acclimated for two weeks and were allotted to five treatments in plastic tanks (26x46x20cm). Each treatment contained 10 fish per tank. The fish were fed experimental diets at T1:0%, T2: 25%, T3: 50%, T4: 75% and T5: 100% Mango Seed Kernel Meal (MSKM) inclusion levels respectively. The highest Mean weight Gain (MWG) and lowest Feed Conversion Ratio (FCR) was recorded in Treatment 2: 25% (48.93±4.88); (0.91±0.07) while the lowest MWG and highest FCR was recorded in Treatment 5: 100% (27.30±3.99); (1.47±0.16). Specific Growth Rate (SGR) was lower in Treatment 5: 100% when compared to other treatments. Feed intake followed a decreasing order. The blood samples collected showed that there was significant differences (p0.05) In conclusion, growth performance and haematological activity could be best improved by substituting mango seed kernel meal at 75% with no implication on growth and fish health.

Efficacy of Nile tilapia (Oreochromis niloticus) juveniles and spinosyns bioinsecticides against aquatic stages of Culex pipiens: An experimental study

Abstract The mosquito Culex pipiens is the most widely distributed dipteran species in all regions of Egypt and the principal vector of Wuchereria bancrofti and certain arboviruses in human beings. For controlling C. pipiens vector, biological tools (e.g., larvivorous fish and bioinsecticides) are more potent and safer options to the environment, human beings, and beneficial organisms than chemical pesticides. The efficiency of O. niloticus juveniles as predatory fish species and two bioinsecticides, spinosad 24% and spinetoram 12%, was investigated against the C. pipiens developmental stages in the laboratory. The first trial evaluated the predatory efficacy of small-sized O. niloticus (2.1–2.6 cm; 250–315 mg) and large-sized O. niloticus (2.5–3.2 cm; 250–315 mg) against the 3rd larvae and pupae of C. pipiens. This is the first report in Egypt confirming the predation potential of O. niloticus as efficient predatory fish against the immature C. pipiens. Large-sized O. niloticus predated a greater number of 3rd of C. pipiens larvae and pupae than the small-sized ones. Furthermore, the daily consumption of C. pipiens larvae by small- and large-sized O. niloticus was significantly higher than the pupae. The second trial assessed the toxicity efficacy of spinosad 24% and spinetoram 12% against C. pipiens larvae and pupae. The results confirmed that the tested bioinsecticides showed higher potency toward C. pipiens larvae than pupae after exposure for 24 h and 48 h. Spinosad was more toxic toward 3rd C. pipiens larvae (LC50 = 0.013 and 0.003 mg/L) and pupae (LC50 = 320.69 and 44.28 mg/L) than spinetoram after 24 and 48 h. Herein, O. niloticus juveniles (as promising native predatory fish) and spinosyns bioinsecticides were more effective against C. pipiens in the larval stage than in the pupal stage. In conclusion, Nile tilapia juveniles and biorational compounds, spinosad 24% and spinetoram 12%, might be considered as promising and favorable environmental biological agents for controlling C. pipiens in Egypt. However, further trials are needed to investigate the potential of these agents in the control of this mosquito vector under field conditions.

Optimum dietary crude protein for culture of genetically improved farmed tilapia (GIFT), Oreochromis niloticus (Linnaeus, 1758) juveniles in low inland saline water: Effects on growth, metabolism and gene expression

A 60-day feeding trial was conducted to determine the effects of dietary crude protein (CP) on growth, metabolism and growth-related gene expression in genetically improved farmed tilapia (GIFT), Oreochromis niloticus juveniles reared in low inland saline water (ISW) of 5 g/l salinity. Three hundred and fifteen fish (initial weight 2.68 ± 0.01 g) were distributed (15 fish/tank in triplicates) in seven experimental groups (20–50% CP with 5% increment) following completely randomized design (CRD) and fed with seven isolipidic (6%), isoenergetic (16.74 MJ digestible energy/kg) and hetero-nitrogenous (20–50 % CP) purified diets, respectively. Results showed inverse relation between percent weight gain (WG%) and feed conversion ratio which were significantly (p < 0.05) varied in overall, linearly and quadratically due to varying dietary CP. Overall and linear trend of protein efficiency ratio and overall, linear and quadratic trend of apparent net protein utilisation were significantly (p < 0.05) decreased with increasing dietary CP. Overall, linear and quadratic trend of whole body CP along with overall and quadratic trend of whole body lipid contents were significantly (p < 0.05) increased and decreased, respectively with increasing dietary CP up to 35 % and then decreased further. Whereas, overall, linear and quadratic trend of whole body ash content was increased significantly (p < 0.05) with increasing dietary CP. Overall and quadratic trend of protease activity in 30–45 % CP fed groups was significantly higher (p < 0.05) than 20 and 50 % CP fed groups; but overall and linear trend of amylase activity in 20−25 % CP fed groups was significantly higher (p < 0.05) than 35–50 % fed groups. Overall, linear and quadratic trend of hepatic glutamate pyruvate transaminase activity in 40 % CP fed group was significantly lower (p < 0.05) than that of 20−25 and 45–50 % CP fed groups and similar to 30–35 % CP fed groups. However, these trends of hepatic lactate dehydrogenase activity of 40–45 % CP fed groups was significantly lower (p < 0.05) than 20–30 % fed groups and similar to 35 and 50 % CP fed groups. Whereas, overall, linear and quadratic trend of hepatic malate dehydrogenase in 35 % fed group was significantly lower (p < 0.05) than 20–30 % CP fed groups and similar to other groups. The hepatic insulin like growth factor-1 (IGF-1) and IGF-1 receptor expression showed high correlation (r=0.92 and 0.90, respectively) with WG%. The optimum dietary protein requirement of GIFT juveniles at 5 g/l salinity in ISW was found to be 34.53–38.10% based on both broken-line linear and second-order polynomial regression with respect to WG% and hepatic IGF-1 expression.

Digestibility of Local Feed Ingredients in Tilapia Oreochromis niloticus Juveniles, Determined on Faeces Collected by Siphoning or Stripping

Eight locally available protein source ingredients in Tanzania were selected for assessment of apparent digestibility (AD) in tilapia Oreochromis niloticus, using faeces samples collected by siphoning or stripping. The selected protein source ingredients were Lake Victoria sardines (FM), brewers spent yeast (BSY), moringa leaves (ML), freshwater shrimp (FSH), marine shrimp (MSH), cattle blood (CB), duckweed (DW) and fish frames (FF). The AD (%) of dry matter (DM), organic matter (OM) and crude protein (CP) was unaffected (p &gt; 0.782–0.901) by the faeces collection method (i.e., siphoning or stripping), with correlation coefficient (r) of 0.98, 0.99 and 0.93 between AD values for DM, OM and CP, respectively, following siphoning and stripping. The AD (%) of DM, OM, CP and gross energy (GE) in the test ingredients differed (p &lt; 0.0001). The AD (%) of DM and OM was lowest in BSY and DW, followed in increasing order by ML, MSH, FF, FSH and CB. In general, the AD (%) of CP was high (&gt;76%), but with a low value (46%) for DW. The AD (%) of GE was closely correlated (r = 0.96) with the AD of OM. In conclusion, FSH, MSH, CB, FF, BSY and ML have acceptable protein digestibility to be used in tilapia diet formulation.

Chronic effects of a binary insecticide Acer 35 EC on Nile tilapia Oreochromis niloticus through a multi-biomarker approach

Acer 35 EC is a widely used insecticide (a binary mixture of lambda-cyhalothrin and acetamiprid) in pest control in many West African countries, particularly in the cotton culture in north Benin. The aim of this study was to investigate the chronic effects of Acer 35 EC on Nile tilapia Oreochromis niloticus juveniles using a multi-biomarker approach under laboratory conditions. For this purpose, fish were exposed to sublethal concentrations of Acer 35 EC (0, 1 and 10% of LC50- 96 h value). After 28 and 56 days of exposure, several biomarkers were measured in males and females including enzymatic activities related to detoxification and oxidative stress, neurotoxicity and immune responses, sex steroid hormones (testosterone, 17β-estradiol and 11-keto-testosterone) and histological alterations of liver, kidney and gonads. An Integrated Biomarker Response (IBR) was then calculated. The results showed a reduction of cholinesterase activity in muscles, and intercellular superoxide anion production in both sexes. Female steroidogenesis and gametogenesis were affected, especially testosterone levels and oocyte growth. More alterations were observed in liver after exposure to Acer 35 EC. In both sexes, IBR values were higher after 56 days than after 28 days of exposure. In conclusion, based on a large set of biomarkers and IBR values, the chronic exposure to low doses of insecticide Acer 35 EC seems to impair different physiological functions in Nile tilapia juveniles on a time-dependent manner, with a stronger impact on females than on males.

Growth Performance, Gut Ecology, Immunocompetence and Resistance of Oreochromis niloticus Juveniles Fed Dietary Curcumin longa

Abstract The growth, gut ecology and immunocompetence of Oreochromis niloticus and the resistance to Aeromonas hydrophila were investigated after been fed with diets containing dietary Curcumin longa for 12 weeks. Diets were formulated to contain 30% crude protein with diet TC1, TC2, TC3, TC4 and TC5 having 0% (control), 0.25%, 0.5%, 0.75% and 1.0% turmeric powder, respectively. Diets were allotted to groups of O. niloticus (mean weight of 1.29± 0.15 g) and replicated thrice for 84 days. Results showed that the highest mean final weight (4.79±0.04 g) was obtained in TC3 and corresponded to the treatment with the highest feed intake. A significantly high (p&lt;0.05) specific growth rate (SGR) was observed in TC3 (0.73±0.03 %day−1) while TC4 (0.57±0.02 %day−1) gave the lowest value. The highest microbial load in the gut was observed in TC1 groups and the least in TC4 groups. Red blood cell count, hemoglobin, packed cell volume did not show significant variation (p&gt;0.05) across treatments. However, white blood cell (WBC) count was significantly higher in TC1 (control). There was an improved immunocompetence, as aspartate aminotransferase (AST) progressively reduces in fish fed supplements. Similarly, there was a better oxidative response in the treated groups with reduced hydrogen peroxidase, increased total protein and glutathione peroxidase. Mortality ranged from 25% in TC4 to 95% in TC1 after the challenge test with A. hydrophila. This study showed that C. longa inclusion at 0.5% is more beneficial when growth and health status of O. niloticus juveniles are considered.

The growth performance and genotoxicity effect of dietary Aloe vera on Oreochromis niloticus juveniles

Growth and all activities of fish depend significantly on the food they consume. However, with the rising price of conventional feedstuffs, there is a need to investigate less expensive and readily available plant source as an additive. This research is designed to study the effect of dietary Aloe vera on the growth performance of Oreochromis niloticus juveniles (41.71±0.78g) and its effect on genotoxicity (MN: Micronucleus; LB: Lobed; BD: Bud; BL: Blebbed; BN: Binucleated; NT: Notched). This research investigated the growth performance and genotoxicity activity of Oreochromis niloticus juveniles in a tank culture system. Aloe vera (fine powder) was used as a test ingredient in the feed formulation at five inclusion levels (T1 = 5g, T2 =10g, T3 =15g, T4 =20g, T5 =25g) and the Control diet (C0) without the test ingredient. Test diets were fed to Oreochromis niloticus juveniles, and each diet was assigned to the treatments and control overall in triplicates. Feeding with test diets was for twelve (12) weeks at 5% of their total body weight daily, which was divided into two and administered at 8 hrs and 16 hrs. The result showed that the highest growth rate (10.99 ± 5.49g) and the lowest FCR (0.68 ± 0.08) were recorded in the fish fed with the Control diet (C0). Better growth and nutrient utilization were achieved at low inclusion levels of Aloe vera, at 5g(T1) (8.98 ± 4.49) and 10g (T2) (6.73 ± 3.28) compared to the higher levels of incorporations of the test ingredient. The mean pH and temperature (°C) and dissolved Oxygen level mg/L are 6.50±0.30, 26.3±0.60 and 4.48±0.52mg/L respectively. The values of micronuclei for the cultured Oreochromis niloticus juveniles were recorded to be (T1 = 5.50 ± 0.50, T2 = 2.00 ± 1.00, T3 = 2.00 ± 0.00, T4 = 2.50 ± 1.50, T5 = 4.00 ± 1.00, and C0 = 7.00 ± 2.00). Nuclear abnormalities were recorded in T2 (BD = 1.00 ± 0.00), T3 (NT = 1.00 ± 0.00), T4 (BD = 1.33 ± 0.47, BN = 3.33 ± 0.47), and T5 (BN = 5.33 ± 0.47, LB = 3.00 ± 1.00, BL = 1.67 ± 0.47) . However, no abnormality was recorded in the fish fed with the Control diet (C0). This result showed that the slight addition of this Aloe vera to the diet of Oreochromis niloticus would enhance productivity.

Adaptability of the Nile Tilapia, Oreochromis niloticus Juveniles to Water Salinity by Controlling Dietary Sodium Chloride Levels

Adaptability of the Nile Tilapia, Oreochromis niloticus Juveniles to Water Salinity by Controlling Dietary Sodium Chloride Levels

Toxicity effect of &lt;i&gt;Kigelia africana&lt;/i&gt; aqueous extract on the haematology and histopathology of juvenile Nile Tilapia (&lt;i&gt;Oreochromis niloticus&lt;/i&gt;)

This study examined the toxicity effect of Kigelia africana on Nile tilapia ( Oreochromis niloticus ) juveniles. The corresponding effects of this plant extract on the health status of the O. niloticus were similarly studied using their haematological and histopathological profiles. The experiment was carried out at the Hatchery Unit of the Federal University of Agriculture, Abeokuta fish farm. Fish were acclimatized for one week and fed twice daily at the rate of 3% body weight. Water in the culture medium was replenished daily. A total of 150 juveniles of O. niloticus were exposed to concentrations of 0.00, 1.75, 2.50, 3.75 and 5.00 g L −1 aqueous extract of Kigelia africana set up in three replicates. This toxicity study showed that aqueous bark extract of K. africana caused significant behavioural changes in O. niloticus . Recorded values of the water quality parameters showed significant difference ( p < 0.05) across the treatments. The haematological indices of the fish were also observed to be affected with increasing extract concentration, compared to the control treatment (0.0 g L −1 ). Similarly, histology of the liver and gills showed variations in distortions and damages to the tissues; with observed severity increasing with increase in extract concentrations. This study suggested that the 96-h LC 50 of K. africana could be greater than 5 g L −1 . The study concluded that caution must be taken in the disposal of this plant in water bodies as extended exposure time and at higher concentrations could pose adverse effects on the stock of juvenile Orechromis niloticus . Keywords: toxicity, Kigelia africana , Oreochromis niloticus , haematology, histopathology

Acute toxicity of benzalkonium chloride mixture with treated produced water to juveniles of freshwater tilapia - &lt;i&gt;Oreochromis niloticus&lt;/i&gt;

This research was conducted to determine the lethal concentration (LC50) of benzalkonium chloride (BAC) mixture with treated produced water capable of causing mortality of at least 50% of the Nile-tilapia-Oreochromis niloticus juveniles in a static 96h acute toxicity. Juveniles of mix sexes of O. niloticus of average length (6.80 cm) and weight (25.05g) were exposed to various concentrations (20.20, 50.50, 101.00 and 202.00 ppm.) of the toxicant with tap water used as control under laboratory condition. The LC50 values at 24, 48, 72 and 96hours were determined to be 96.427, 73.799, 73.799 and 69.772 ppm, respectively. Water quality check and general fish behaviour (respiratory distress, loss of balance, erratic swimming and death) were observed. Regression equation(y =-0.270 + 93.44) and correlation (R2 = 0.751) obtained from the study depict direct positive relationship between fish mortality and BAC mixture. Hence, unregulated release of benzalkonium chloride and treated produced water into aquatic environment is capable of causing acute toxicity to juveniles of O. niloticus. Its disposal into the environment should therefore be discouraged.Keywords: Acute-toxicity, LC50, Benzalkonium-chloride-mixture, Nile tilapia

Comparative study of three locally available feeds on the growth and nutritional quality of Oreochromis niloticus juveniles

The aim of the present study was to evaluate the effects of three feeds formulated for three fish farming agroecological areas of Cote d’Ivoire on the growth and nutritional quality of Oreochromis niloticus juveniles. Feeds were formulated at 30% crude protein with locally-sourced raw materials available by area. The use of different ingredients at different levels for feeds formulation made variations in the nutritional compositions and costs of the three feeds produced. The average male weight of O. niloticus juveniles, 26.89±2.98 - 27.35±2.74 g, were stocked at a density of 3 fish/m2 and were hand fed at 5-3% body weight two times daily, six days per week during 120 days in the triplicate earthen ponds. At the end of the feeding trial, daily weight gain values varied between 1.12±0.08 g/day and 1.21±0.06 g/day and survival rate ranged between 99.44±0.00 and 100%. No significant difference (p