Niloticus Juveniles Research Articles

Efficacy of sodium bicarbonate (Baking soda) and clove powder (Syzygium aromaticum) as anaesthetic agents for Nile tilapia (Oreochromis niloticus, linnaeus 1758) juveniles

ABSTRACT Anaesthetics in aquaculture serve as a stress avoidance mechanism, mitigating stress-related impacts during fish handling and transportation. This study assessed the efficacy of sodium bicarbonate and clove stem powder as anaesthetic agents for Nile Tilapia juveniles. Four hundred and twenty uniform O. niloticus juveniles (5 ± 0.5 g, 74 ± 5 mm) were exposed to varying concentrations of sodium bicarbonate (10, 15, 20, 25, 30, 35, 40 g/L) and clove stem powder (0, 1, 3, 5, 7, 10, 15 g/L) in 20 L transparent plastic tanks. The results showed an inverse relationship between anaesthetic concentration and induction time, a direct relationship with recovery time, and an inverse correlation between induction and recovery times for both agents (P < 0.001). The Appropriate concentrations were determined as 25 g/L for sodium bicarbonate and 10 g/L for clove stem powder. At these levels, induction and recovery times met ideal criteria (3-5 min induction, 5-10 min recovery), with fish exhibiting normal behavior and 100% survival after a week of monitoring.

Intestinal Histopathological Aberrations in Oreochromis niloticus Juveniles upon Dietary Florfenicol Administration.

The aquaculture use of antibiotics can cause detrimental effects on fish organs and gut microbial dysbiosis. The impact of florfenicol (FFC) on fish intestinal histology, an approved antibiotic, remains unclear. This study aimed to investigate the effects of FFC on Oreochromis niloticus juveniles by administering FFC at 10mg and 30mg/kg biomass/day for 30 consecutive days to mimic long-term use. A dose-dependent reduction in feed intake, survival and biomass, with an upsurge in mortalities was observed. Even the therapeutic dose instigated mortalities on day 30 of FFC dosing (FD). Histopathological analysis revealed mild to moderate alterations, including loss of absorptive regions, epithelial degeneration, necrotized areas, intercellular enterocytic space and swollen laminar propria. Post-dosing, the observation of the detachment of lamina propria from the epithelium indicated imminent irritability. Goblet cells reduced drastically on day 30 FD, accompanied by an increase in intraepithelial lymphocytes. However, cessation of dosing for 13 days resulted in the reclamation of goblet cells and absorptive regions, indicating that the intestinal tissues underwent considerable repair after lifting antibiotic pressure. These findings suggested that O. niloticus can tolerate dietary FFC but emphasize the need for responsible use of antibiotics in aquaculture.

Dose-Response Relationship and Histo-morphological Alterations on Oreochromis niloticus Juveniles Following Exposure to Ethanolic Extract of Latana camara

Aim: This research intends to evaluate the toxicity of latana camara and ascertain if it can be useful as a plant-based additive in the formulation of fish feed.&#x0D; Study Design: The study was conducted using two replicate (Batch A and B) for 96 hours under controlled laboratory conditions. Five concentrations ranging from 0, 5, 10, 15, and 20 mg/l were prepared from the ethanolic extract (EE) of L. camara for the toxicity test.&#x0D; Place and Duration of Study: Experiment was conducted in Akwa Ibom State University, Obio Akpa Campus, Akwa Ibom State between February, 2023 and June, 2023.&#x0D; Methodology: Total of two hundred (200) juveniles were collected for the studies. One hundred (100) juveniles were used during range findings test and the left over for the actual toxicity test. Prior to commencement of the toxicity test, experimental fish were allowed to acclimatize. Each of the ten (10) plastic aquaria was stocked with ten (10) O. niloticus juveniles. The prepared plant extract at varying concentration was added to each stock aquaria and allowed to stand for 96 hours for mortality examination. Gills tissues were isolated from the fish samples in each of the concentration after 96 hours for histopathological examinations.&#x0D; Results: The experimental animals showed differential percentage mortalities with toxicant concentrations. The 96 hours LC50 for O. niloticus for both batches (A and B) was given at 7.346 mg/l representing a log transformed concentration of 0.866 mg/l. The different batches of O. niloticus (P = .05) had no significant difference in mortality. The results of the present study suggest that the EE of L. camara had severe impacts on the test organism resulting in mortality. The effects of L. camara on the gills of O. niloticus Juveniles showed severe impacts on the test organisms. Five samples were taken from each of the concentrations to examine the effects of the extract on the gills of O. niloticus. There were no observed changes in the gills of the control group as compared to other treatment which showed evidence of histological alterations.&#x0D; Conclusion: From the findings, it is observed that extract obtained from L. camara is toxic to aquatic life and cannot be recommended as a plant-based additive in the formulation of fish feed.

Safety, tolerability and biological responses of Oreochromis niloticus juveniles upon oral oxolinic acid administration.

In aquaculture, oxolinic acid (OA) is used as a second-line treatment at 12 mg/kg biomass/day for seven consecutive days. The present study evaluated the biosafety of 21 days of dietary administration of OA at 0, 12, 36, 60 and 120 mg by assessing the growth, biochemical, erythrocytic morphological and histopathological alterations and residue levels in Oreochromis niloticus. A significant dose-dependent reduction in feed intake and biomass and an increase in mortalities and erythrocytic cellular and nuclear changes were recorded. Significant elevations in plasma glucose, creatinine, alkaline phosphatase, alanine transaminase and aspartate transaminase and a decline in calcium and chloride levels were documented. The kidney, liver and intestine histoarchitecture showed mild to marked alterations. The edible tissue OA residues peaked on day 21 and decreased upon cessation of administration in all the dosing groups. The residue levels in the muscle of the recommended dose group were well within the maximum residue limit set by the European Medicines Evaluation Agency. Although the current study hinted at the safety and tolerability of OA even during long-term usage in O. niloticus in Indian conditions, care must be exercised for its aquacultural application because of its listing as a critically important medicine for humans.

Studies on Mortality and Histopathological Alteration on the Gills of Oreochromis niloticus Juveniles Following Exposure to Ethanolic Extract of Phramenthera capitata under Laboratory Conditions

The study was conducted using two replicate (Batch A and B) for 96 hours under controlled laboratory conditions, with five different concentrations of the extract ranging from 0 to 40 mg/l. The results of the study revealed that the extract had a concentration-dependent toxic effect on the test organisms, with induced behavioural changes such as abnormal and uncoordinated swimming movement, restlessness, respiratory difficulties, and attempts at jumping out. The alterations of physico-chemical parameters of the test water were also observed, indicating the adverse effects of the extract on the aquatic environment. The 96 hours LC50 for Oreochromis niloticus was determine to be 22.124 mg/l representing a log-transformed concentration of 1.345 mg/l. This is the concentration where 50% of the test organisms is expected to die at the end of the 96 hours’ bioassay. The histopathological examination of the gills revealed pathological changes in the test organisms at concentrations of 20, 30, and 40 mg/l whereas no histomorphological changes was observed at 0 and 10 mg/l concentrations of the extract. The result of the present findings suggests that ethanolic extract of P. capitata had severe impacts on the test organisms resulting in mortality and gill damage.

Influence of Culture Tank Colours on the Water Quality, Growth Performance and Feed Utilization of Oreochromis niloticus (Linnaeus, 1758) Juveniles

The study was conducted over a period of fifty-six (56) days to investigate the effects of different colours of culture tanks on the water quality, growth, and feed utilization of Nile tilapia (Oreochromis niloticus) juveniles. O. niloticus of mean body weight of 8.5g were stocked and fed twice daily with a commercial diet containing 42% crude protein. The experiment had four treatments based on tank colours; white, green, black and blue coloured tanks. Some water quality indices were assessed once in a week while the fish were weighed at the end of the experiment to compute the performance indices. The data were presented using mean and standard error and comparative analysis was done using one way ANOVA at 95% confidence interval with Duncan multiple range test as the follow up test. The water quality parameters examined during the study were not significantly different among the treatments. All the selected water quality parameters were within the acceptable range for tropical fish culture. While there was no significant difference in final weight, weight gain, percentage weight gain, and specific growth rate among the treatments, black tanks showed slightly higher values with 10.89±0.89 g, 2.54±0.94g, 30.47±11.43%, and 0.47±0.16%/day, respectively. Higher feed intake and FCR were recorded in green tank (10.08±0.61 g and 7.92±2.70 respectively) and the least was observed in black tank (9.32±0.12g and 4.23±1.51). The percentage survival of the fish was different significantly among the treatments (P&lt;0.05). Fish reared in white background showed the highest survival (100%) which was different significantly from all other treatments. The blue and black tanks showed slightly higher values of viscerosomatic index and hepatosomatic index with 7.22±1.00% and 2.02±0.25%, respectively, while black and white tanks had the least values with 4.44±1.11% and 1.64±0.15%, respectively. The results showed that O. niloticus juveniles can be reared in all the tanks with no negative implication on their performances. However, black and white tanks showed better potential towards improved growth and feed utilization, while white tank led to better survival rate and tended towards better well-being as indicated by the skin pigmentation and hepatosmatic index. Therefore, rearing of O. niloticus juvenile in white tank is recommended over other colours.

Effects of Pretilachor Pyribenzoxim Pollution on the Water Quality, Serum Biochemical Indices, and Behavioural Response of Oreochromis niloticus Juveniles

Aims: The effects of Pretilachor pyribenzoxim (PP) pollution on the water quality, serum biochemical indices, and behavioural response of Oreochromis niloticus Juveniles were studied.&#x0D; Study Design: The completely randomized design was used in this study.&#x0D; Place and Duration of Study: The experiment was carried out in the Central Laboratory of the Fisheries and Aquaculture Department, Faculty of Agriculture, Adekunle Ajasin University Akungba-Akoko, Nigeria, between January and March 2023.&#x0D; Methodology: The experiment was carried out in 30 L of non-chlorinated and aerated water in rectangular plastic tanks (45cm x 30cm x 30cm). 250 juveniles O. niloticus of both sexes were collected from Federal University of Technology, Akure, Ondo state and acclimatized for 14days in the laboratory. During rearing period, the fish were fed coppen feed at 2% body weight. In a definitive test, a group of 10 fish specimen (11.3-17.5cm length and 10.5-32.3g weight) were treated at random to nominal PP doses of 0.0, 0.10, 0.125, 0.150, 0.175, and 0.2 ml being diluted in 30 litres of water and labelled T1. T2, T3, T4, T5 and T6, respectively in triplicate. The LC50 of PP, test water's physicochemical, behavioural responses and serum biochemical indices were determined.&#x0D; Results: The dissolved oxygen depleted (P&lt;0.05) in T5 and T6, compared to T1 and the rest of the treatments. The water conductivity increases (P&lt;0.05) with an increased concentration of PP contamination. The water's total dissolved solids levels increased progressively with an increase in PP concentration. The total dissolved solids in T5 and T6 were similar (P&gt;0.05) to T4 but lower (P&lt;0.05) than T1 and T2. Juveniles in treatments 2, 3, 4, 5 and 6 shows behavioural responses such as loss of reflex, fin deformation, erratic swimming, air gulping, and moulting. The serum total protein of the juveniles in treatments 2, 3, 4, 5 and 6 was lower (P&lt;0.05) than T1. Serum creatinine level increased with increased PP contamination from treatments 1 to 6. The serum aspartate aminotransferase (AST) of the juvenile in T3, T4, T5 and T6 were higher (P&lt;0.05) than in T1. The serum Alanine aminotransferase (ALT) of the juvenile in T2, T3, T4, T5 and T6 were significantly (P&lt;0.05) higher than T1.&#x0D; Conclusion: The exposure of juvenile O.niloticus to PP contamination affected the physicochemical properties of water, behaviour and Serum biochemicals of juvenile O. niloticus fish. Hence, leaching of pp into water bodies through Agricultural activities should be mornitored to reduce lost of fish which can lead to economic detune.

Sub-lethal toxicity of indigo dye (Indigofera tinctoria) on Oreochromis niloticus juveniles

BackgroundTextile dyes which are eliminated as unfixed dyes through the effluent from textile industry cause deleterious effect on the fresh water fish. Thus, toxicity tests were conducted using indigo dye on Oreochromis niloticus juveniles (mean weight 30.00 ± 0.73 g) as a test fish under bioassay system. Varying concentration of 0.00 (control), 0.5, 1.0, 1.5, 2.0, and 2.5 mg/l containing graded levels of Indigofera were applied in experimental tanks to determine the lethal concentration. The LC50 of dye at 96 h was 1.3 mg/l of water. The histopathology (heart, gills, kidney and spleen) and water quality parameters (Dissolved oxygen, pH and temperature) were determined using standard methods and behavioural responses were observed.ResultsHistopathology of heart, gills, kidney and spleen revealed degeneration of cells, space formation, slight cellular changes and vacuolation among the treatments especially in the higher concentration of 1.5 mg/l, 2.0 mg/l, and 2.5 mg/l of the dye solution used except in the control. The pH and DO of control were significantly different from the experimental units while there was no significant variation in the temperature of the control and all the experimental units. Effects of indigo dye on water parameters were significant (P < 0.05) throughout the experiment. Behavioural responses exhibited by the experimental fish include irregular swimming, hyperventilation, rapid opercula movement, and restlessness. The dye concentration and exposure period both boosted these behaviours.ConclusionsThe findings of this study indicated that indigo dye solution is toxic to fish, and that fish opercula movement and mortality were influenced by the dosage of each concentration and the duration of exposure.

Impact of Different Concentration of Thorn Apple (Datura stramonium) Extract on Growth, Histopathology and Blood Profiles Response to Sub- Lethal Exposure of Nile Tilapia (Oreochromis niloticus) Juveniles

This study investigated the toxic effects of Datura stramonium leaves extract on growth, histopathology and blood profiles of Oreochromis niloticus juveniles. Datura stramonium leaves extract of various concentrations were prepared at 0.00 (control), 0.002, 0.02 and 0.2 ml/L for 28 days and 10 days withdrawal in triplicate. Twenty (20) Oreochromis niloticus fingerlings (6.05±0.01g) were randomly distributed into each experimental bowl containing 45 L of treatment concentrations. Biological evaluation, blood profiles parameters, and histology of the exposed fish were determined. The result shows an increase within the weight gain and the weight gain was higher in the exposed groups expect TAL 4 than the control. There was no significant difference (P&gt;0.05) among the treatments. The haematological response to D. stramonium exposures shows that the values of packed cell volume and haemoglobin were higher in the exposed groups compared to the control while the white blood cell, neutrophils, and lymphocytes decrease as the concentration of the plant increases and were lower than the control. The result revealed a higher value of total protein and albumin in the exposed groups compared to the control. There were decreased in the values of ALT and AST when compared to the control and the values of total protein, albumin, ALT and AST after 10 days of withdrawal show a similar trend in values obtained before the experiment. The result of histopathology shows no observable lesions were observed in control group while there were moderate alterations in gills, liver and the intestine of the exposed groups. This investigation revealed that continuous use of the D. stramonium leaves extract in the aquatic environment will affects the growth, blood profiles and histopathology of the exposed fish.

The effect of Spirulina (Arthrospira platensis) as a microbial diatory feed supplement for juvenile of Nile Tilapia (Oreochromis niloticus)

Tilapia is the second most farmed fish in tropical and sub-tropical countries worldwide. This study investigated the effect of replacing fish meal by Spirulina platensis (groups fed with 5%, 10% and 15% Spirulina) on the growth of Nile tilapia O. niloticus juveniles. Intestinal microbiota of tilapia has been studied by MiSeq Illumina sequencing. No significant differences (P &gt; 0.05) were observed for the protein, carbohydrate and lipids of fish fed with control food and different concentrations of spirulina. However, the Margalef species richness of the intestinal bacteria of tilapia fed with spirulina was significantly higher (P &lt; 0.05) compared to the control samples. Evenness was significantly higher (P &lt; 0.05) for tilapia fed with food substituted with the highest concentration of spirulina. Also, few potentially probiotic genera, like Bacillus and Actinomycetes were detected in the gut of the experimented Tilapia. On the other hand, the highest percent of potentially pathogenic genera was recorded for the genera Pseudomonas and Corynebacterium. In most cases, the highest abundances of potentially pathogenic species were found in control samples. As manipulation of the feed was shown to improve Tilapia microbiota, which could lead to further improvements in aquaculture production.

Digestibility, Growth and Hepatosomatic Index of Oreochromis Niloticus (Linnaeus, 1758) Fed Diets Containing Blanched Lemna paucicostata (Hegelm)

This study evaluated digestibility, growth and hepatosomatic index of Oreochromis niloticus fed diets containing blanched Lemna paucicostata as a replacement for toasted soybean meal. Five iso-proteinous diets were formulated using feed solution software, blanched Lemna paucicostata was used to replace toasted soybean meal progressively at 0%, 25%, 50%, 75% and 100% respectively. Fifteen Hapa nets of 1m2 each were used. Ten Oreochromis niloticus juveniles were introduced into each of the nets. The fish were fed at 5% body weight three times daily for a period of six months. There was significant difference (P≤0.05) in the apparent protein digestibility coefficient among the treatments and the control. Highest apparent protein digestibility coefficient of 92.94% was recorded in the diet containing 75% blanched L. paucicostata meal while the least value of 86.86% was obtained in the diet with 100% L. paucicostata meal. The fish fed diet containing 75% blanched L. paucicostata meal recorded significantly highest (P≤0.05) mean final weight of 468.01g followed by the fish fed with 50% blanched L. paucicostata meal with 453.68g, the fish fed 100% blanched L. paucicostata meal recorded significantly lowest (P≤0.05) value of 401.54g. The fish fed diet containing 75% inclusion level of blanched L. paucicostata meal gave the best protein, lipid, ash and carbohydrate digestibility of 92.94%, 90.62%, 52.29% and 80.56%, respectively and also gave the best growth performance and hepatosomatic index.

Incorporation of ω3 fatty acids in the diets of Nile tilapia juvenile (Oreochromis niloticus L.): effects on growth performance, fatty acid composition, and tolerance to low temperature.

In order to increase the low-temperature resistance of Nile tilapia, the purpose of this study was to determine the potential effect of ω3 fatty acid incorporation in Oreochromis niloticus diet. To perform this, two experimental diets containing soybean oil (D1) and cod liver oil (D2) have been supplied to juvenile tilapia for 30days. According to our results, similar improvements in the two diets have been recorded for growth performance of O. niloticus including the final body mass, specific growth rate, and feed conversion ratio. Our results showed that fish fed with diet D2 promoted high polyunsaturated fatty acids mainly n-3 series (PUFA (n-3)) percent, highlighting the increased levels of docosahexaenoic (DHA) and eicosapentaenoic (EPA) as well as the activation of their conversion enzyme ratios D5D and D6D desaturases. The second objective was to assess the effect of the two experimental diets on low water temperature tolerance. This was done by exposing juvenile fish at the end of the first experiment to 16, 14, 12, 10, and 8°C for 12h, 24h, and 48h. The sub-lethal LT50 of O. niloticus fed with diet D1 was 10.6, 11.4, and 13°C respectively, after 12h, 24h, and 48h. This pattern was commonly observed for O. niloticus fed with D2, showing that the subLT50 were 10.3, 11.1, and 12°C during the same period. These results demonstrate that O. niloticus juveniles fed with diet D2 are more tolerant to low temperatures than those fed with diet D1.

Yeast Rhodoturula glutinis as a modulator of innate immune and oxidative stress-related genes in Oreochromis niloticus cultured in a Biofloc system

The effect of live yeast Rhodoturula glutinis was evaluated on juvenile Oreochromis niloticus cultivated in a Biofloc system. Growth performance and the expression of innate response and relevant oxidative stress genes were evaluated after a 12-week feeding trial. Three experimental treatments were evaluated in a conventional tilapia culture (control), Biofloc culture (BFT), and Biofloc with the addition of the live yeast R. glutinis 1×106 CFU g-1 (BFT+Rg), with four replicates per treatment. In all cases, commercial food was supplied to the organisms (32% protein and 5% lipids). O. niloticus juveniles (7.02 ± 0.04 g) were randomly distributed in 12 tanks, each with 15 animals. BFT+Rg treatment showed a significant increase in weight gain compared with the other treatments. Significant improvements were found in Fulton's condition factor, feed conversion rate, and hepatosomatic index under Biofloc conditions, BFT, and BFT+Rg treatments. No significant differences were observed in survival. R. glutinis directly influenced gene expression in the liver and intestine. The expression of tnfa, tgfb, hsp70, and gpx, genes in the liver significantly increased in the BFT+Rg treatment compared with the other treatments. Similarly, a significant increase was found in intestinal il1b, tnfa, tgfb, trf, hsp70 gpx, and cat expression patterns in the BFT+Rg treatment. Based on the performance and immune response, the present study suggests the use of R. glutinis as a strategy to increase the productivity of tilapia in Biofloc culture.

Anaesthetic and Histological Effects of Lidocaine Hydrochloride on Oreochromis niloticus Juveniles

This study investigated the toxicity of Lidocaine Hydrochloride-sodium Bicarbonate (LHB) on Oreochromis niloticus juveniles (20.75 g). The histological tissue examinations were used to assess the effects of the anaesthetic agent (LHB) on the fish after exposure. Varying concentrations of LHB in increments of 10mg/L ranging from 60mg/L to 100mg/L were used for the static bioassay. There was a decrease in induction and recovery time with an increasing concentration of LHB showing a significant positive correlation (R2= 0.9721; p&lt;0.05) and (R2=0.7338; p&lt;0.05) respectively. Anaesthetic values of LHB for O. niloticus at an induction time of less than 4 minutes and recovery time of less than 3 minutes were observed. No mortality occurred during the experiment. Histological examination of the gills, liver and kidney of O. niloticus after exposure showed different pathological changes. The gills and liver of the fish exposed to 100 mg/L concentration showed no sign of histological changes. However, the results obtained showed a severe histological effect on the kidney of juveniles Oreochromis niloticus at 100 mg/L of LHB.

Biological Responses of Nile tilapia Oreochromis niloticus as Influenced by Dietary Florfenicol

Antibiotics are used in the treatment of bacterial diseases in commercial aquaculture. In this study, we the biological responses of Oreochromis niloticus juveniles upon dietary florfenicol (FFC) administration at 15 mg (1×) and 45 mg kg biomass−1 day−1 (3×) for 10 days in terms of feed intake, survival, biomass, hematological, erythro-morphological, serum biochemical, and histopathological aberrations as compared with controls. FFC caused a dose-dependent reduction in feed intake, survival, and biomass, with marked variations in hematology, hematological indices, and erythrocytic cellular and nuclear abnormalities, suggesting its apparent cytotoxic and nucleotoxic effects. The serum biomarkers increased significantly in a dose-dependent manner, except for calcium and chloride, which decreased significantly. The therapeutic dose (1×) group exhibited marked histopathological aberrations, such as renal tubular epithelial degeneration and a widened lumen in the kidney, as well as glycogen-type vacuolation and cytoplasmic degeneration in the liver during the dosing period. The extent of kidney and liver tissue damage was more prominent in the 3× group. The 1× serum biomarker levels became normal, with the exception of alkaline phosphatase, within 3 weeks of suspension of dosing. The recovery of the measured parameters and histopathological and erythro-morphological changes suggested that the therapeutic dietary biological responses induced by FFC are reversible and safe for O. niloticus.

The Effect of Neonicotinoids Exposure on Oreochromis niloticus Histopathological Alterations and Genotoxicity

This study aimed to examine the side effects of selected neonicotinoids (Acetamiprid, Aceta, and Imidacloprid, Imid) on Oreochromis niloticus juveniles. The acute toxicity, Probit method, revealed an LC50 of 195.81 and 150.76 ppm for Aceta/96 h and Imid/72 h respectively. The fish were divided into three groups that were exposed, for 21 days (n = 5/replicate), to 1/10 of the LC50 of either neonicotinoids, however, the third was an unexposed control group. Results of erythrocytic micronucleus (MN), and nuclear abnormalities (NA) showed that Aceta and Imid exposure caused a significant (p < 0.05) increase in MN by ~ 2.2 and ~ 10 folds, respectively relative to control. NAs occurred at the order of kidney-shaped > budding > binucleated in Aceta, however, budding > binucleated > kidney-shaped was noticed in the Imid group. Histopathological changes in gills, liver, and muscles were observed significantly in both exposed groups with more severity in the Imid group. Collectively, Aceta and Imid have potential genotoxicity and histopathological alterations in O. niloticus.

Dietary emamectin benzoate induces dose-dependent variations in haemato-biochemical and erythrocyte-metric parameters of Oreochromis niloticus (L.)

Intensive fish farming often leads to the emergence of infectious and parasitic diseases, which require aquadrugs to control them. The present study evaluated the effects of 1× (50 μg/kg biomass/day) and 3× (150 μg/kg biomass/day) dietary emamectin benzoate (EB)-dosing on healthy Oreochromis niloticus for 7 consecutive days in comparison with control. Dietary EB caused a significant dose-dependent reduction in feed intake and an increase in mortalities. The total erythrocyte counts (TECs), monocyte counts (MCs), haemoglobin (Hb), haematocrit (Ht), and mean cell haemoglobin concentration (MCHC) reduced significantly. Contrarily, the counts of total leukocytes (TLCs), thrombocytes (TCs), lymphocytes (LCs) and neutrophils (NCs) increased significantly within 7 days of EB-dosing (ED) in both groups. The TECs, Hb, TCs and MCs normalized on day 35 post-EB-dosing (PED), while Ht, MCH, LCs, and MCs recuperated on day 14 PED. Both groups experienced a significant increase in serum glucose, alkaline phosphatase, alanine transaminase, aspartate transaminase and creatinine levels as well as a decrease in calcium, chloride ions and acetylcholinesterase levels during the ED period. The alkaline phosphatase and creatinine levels of the 1× group recovered on day 14 and 28 PED, respectively but not in the 3× group. The dosed fish documented reduced erythrocyte cellular and nuclear morphometry like larger axis, minor axis, volume, and surface area, which recovered during the PED period, except for the nuclear volume. The results suggested the tolerability of O. niloticus juveniles and their ability to mount adaptive responses to the effect of EB to recuperate with the suspension of dosing.

Histopathological aberrations and oxidative stress responses in Nile tilapia Oreochromis niloticus as influenced by dietary florfenicol and its metabolites

The intensification of aquacultural practices demands the regulated use of antibiotics to contain diseases. This study investigated the accrual and depletion of florfenicol (FFC) and its metabolite florfenicol amine (FFA) in Oreochromis niloticus juveniles following dietary administration of 15 and 45 mg FFC/kg biomass/day for 10 days, the oxidative stress responses and histopathological alterations in the kidney and liver tissues. The therapeutic dose caused no mortalities but reduced the feed intake significantly. The induction of oxidative stress in the liver and kidney tissues upon FFC-dosing was revealed by the increase in malondialdehyde, ferric reducing antioxidant power, total nitric oxide, and decrease in glutathione-S-transferase on day 10. The dietary FFC caused degeneration of renal tubular epithelium, inflammation, mineralization, hydropic swelling and necrosis in the kidney and glycogen-type vacuolation, cytoplasmic degeneration, cellular hypertrophy, and nuclear abnormalities in the liver signifying its nephrotoxic and hepatotoxic potential. The elimination of FFC was rapid in the liver and kidney but it persevered in muscle for 3 weeks. The depletion of FFA was faster in the liver and muscle, while it persevered in the kidney, signifying the probable reaction between free radicals and FFC metabolites. The withdrawal period was computed to be 6 days. Within 3 weeks of termination of dosing, the changes in biomarkers and histoarchitecture were recuperated. Though the dietary FFC induced oxidative stress and alterations in the kidney and liver histoarchitecture, our findings suggested that FFC was well tolerated by O. niloticus and is practically safe at the therapeutic dose.

Role of dietary Spirulina platensis and betaine supplementation on growth, hematological, serum biochemical parameters, antioxidant status, immune responses, and disease resistance in Nile tilapia

Spirulina platensis is, a freshwater microalga, broadly used worldwide. It not only stimulates the immune systems of aquatic organisms but also provides a protein-rich diet and commonly used in the manufacture of aquafeeds. This study was planned to evaluate the growth performance, hepato-renal, and immune response biomarkers of Spirulina and Betaine on Nile tilapia (Oreochromis niloticus) and their protective effect against infection with Aeromonas hydrophila. O. niloticus juveniles (20.22 ± 0.86 g) were divided into four groups (n = 10 per replicate). For 8 weeks, the first and second groups (TS&TB) were fed with 0.5% and 0.3% concentrations of Spirulina and Betaine supplemented diets, respectively; the third group (TSB) was fed with a Spirulina and Betaine mixed diet; the fourth group was fed with a basal diet (without supplementation, T0), which served as control. Dietary inclusion of Spirulina and Betaine significantly improved (P ˂ 0.05) the weight gain, final weight, and food conversion ratio, especially in the TS group. The activities of hepatic malonaldehyde were unchanged in TS & TSB groups and the muscular significantly decreased (P ˂ 0.05) in the same groups, while both increased in the TB group; meanwhile, levels of glutathione reductase were significantly upregulated in all treated groups. Serum interleukins, TNF- alpha, and IL-10 levels were also significantly reduced in all treatment groups. A significant protective power against pathogenic Aeromonas infection was evidenced in all treated groups. Findings in this study highlight the reputation of Spirulina and Betaine as immunostimulants and protective agents against A. hydrophila infection in O. niloticus.

Frequency of Water Change on Growth Performance, Nutrient Utilization and Liver Histology of Nile Tilapia (Oreochromis niloticus, Linnaeus, 1758)

The study was conducted to investigate the frequency of water change on the growth performance, nutrient utilization and body indices of Oreochromis niloticus juveniles. O. niloticus of average body weight of 15 g were stocked and fed with 42% crude protein diet twice daily. The experiment had three treatments with 50% changing of water, every 2days, every 4days and every 7days. The water quality parameters were not significantly different among the treatments except for pH. Weight gain, percentage weight gain and specific growth rate were slightly higher in the 4days interval of changing water with values; 57.65±8.95 g, 33.93±5.16 % and 0.52±0.07 % day-1 respectively. Higher but not significant yield in relation to the volume of water used was obtained in 7days interval (0.46±0.09 Kg m-3). Slightly higher values of condition factor, viscerosomatic index and hepatosomatic index were recorded in the 4days water changing interval. Higher glycogen content was observed in water changes every 4days. All the livers were healthy with the mildest vacuolations in the treatment with water changes once in a week. The results showed that O. niloticus juveniles can be reared with water changes every 7days with no negative consequences. Water changes every 4days tended towards the best.