Length-weight relationship and condition factor of Nile tilapia ( Oreochromis niloticus) fed diets supplemented with guava and star gooseberry leaf extract.

Background: Nile tilapia ( Oreochromis niloticus) is predominant cultured species in aquaculture. However, there is a scarcity of literature regarding relationship between guava and star gooseberry leaf extract and the condition factor. Thus, the present study aims to investigate the effect of guava and star gooseberry leaf extract-supplemented diets on the specific growth rate, length-weight relationship, and condition factor of Nile tilapia. Methods: Six hundred and thirty Nile tilapia (8.7±0.4 g) were randomly distributed among twenty-one tanks (30 fish per tank) within a recirculation system. Over a 60-day period, the fish were fed diets supplemented with 5g/Kg and 10g/Kg of guava leaf extract (GLE-5, GLE-10), star gooseberry leaf extract (SGLE-5, SGLE-10), and a mixture of both (MxLE-5, MXLE-10). Subsequently, specific growth rate, length-weight relationship, and condition factor were determined. Results: After 60 days, the specific growth rate was significantly higher in all the GLE, SGLE, and MxLE groups compared to the control group. The final lengths and weights differed significantly both in the control group and all the GLE, SGLE, and MxLE groups. The analysis of the regression equation indicated a positive correlation (r = 0.970, 0.977, 0.976, 0.974, 0.974, 0.974, and 0.969) between the length and weight of Nile tilapia in the control group and in all the GLE, SGLE, and MxLE groups. The regression exponent " b" values in all the GLE, SGLE, and MxLE groups were >3, indicating a positive allometric growth pattern in Nile tilapia compared to the control ( b=2.866), which exhibited a negative allometry. The final condition factor values did not differ significantly in either the control group or any of the plant extract groups. Conclusions: Nile tilapia exhibited positive allometric growth patterns and maintained good health when fed with GLE, SGLE, and MxLE groups. Therefore, these plant extracts demonstrate suitability for commercial Nile tilapia production.

Dietary biogenic selenium nanoparticles improve growth and immune-antioxidant indices without inducing inflammatory responses in Nile tilapia.

The present study evaluated the use of green-synthesized selenium nanoparticles (SeNPs), using the microalgae Pediastrum boryanum as a diet additive in aquaculture to improve the growth performance, health, and immune response of Nile tilapia. Nile tilapia were fed different concentrations of green SeNPs (79.26 nm) as follows: 0, 0.75, and 1.5 mg/kg of SeNPs for 8 weeks. Following the trial, growth performance, biochemical indices, antioxidant and pro-inflammatory cytokine-related genes, and tissue histological examinations were performed. The study showed that SeNPs significantly improved (P < 0.05) growth performance and innate immune parameters (P < 0.001, IgM, and lysozyme) at both supplemented doses compared with the control. The protein profile and liver function enzymes were normal compared with those in the control group (P > 0.05). Serum malondialdehyde and superoxide dismutase levels were not significantly changed, while reduced glutathione and catalase were significantly enhanced (P < 0.01, P < 0.05) in the SeNPs 1.5 mg/kg compared to the control group. No inflammatory response was detected upon SeNP supplementation, as indicated by the absence of changes in the expression of pro-inflammatory cytokine genes. The earlier assays' results were histopathologically evidenced, where hepatic and splenic tissue architectures in SeNPs groups did not reveal any deviation from the control group. Our findings indicate that green selenium nanoparticles can potentially improve the growth and immunological response of Nile tilapia, offering opportunities for incorporating health benefits into functional foods and nutraceuticals, which corresponds to the increasing consumer interest in eco-friendly, environmentally sustainable dietary supplements.

Elevated temperature impairs gonadal development by suppressing the expression of the genes for kisspeptin, GnRH1 and GTH subunits in Nile tilapia Oreochromis niloticus.

Temperature is a preeminent factor in the regulation of fish reproduction and hinders gonadal development beyond a specific threshold. To comprehend the molecular mechanism responsible for reproductive suppression at different temperature, expression of the genes encoding kisspeptin (kiss2), gonadotropin-releasing hormone (gnrh1) and their receptors (gpr54, gnrh1r) in the brain, and the gonadotropin (GTH) subunits (fshb and lhb) in the pituitary were studied in juvenile Nile tilapia (Oreochromis niloticus) along with gonadal histology. Fish were acclimatized to three distinct temperatures, including 31 °C, 34 °C and 37 °C for 14 days. The mRNA levels of kiss2, gpr54, gnrh1, and gnrh1r were significantly decreased at 37 °C compared to 31 °C and 34 °C in the both sexes. In parallel, the expression level of fshb in the both sexes and lhb in the female were significantly lower at 37 °C in the pituitary. Histologically, the gonads of both sexes had normal growth of gametes at control temperature (31 °C), whereas the spermatogenesis and oocyte maturation were slowed down and atretic oocytes were found in the ovary at 37 °C acclimation temperature. Taken together, the results imply that elevated temperature beyond the specific threshold may have a negative impact on reproduction by suppressing the gene expressions of kisspeptin/GnRH1/GTH system and eventually restrains normal growth and maturation of gametes in the both sexes of Nile tilapia.

Interactive effects of water temperature and dietary protein on Nile tilapia: growth, immunity, and physiological health.

Optimizing fish performance depends on several factors, with dietary protein levels and rearing temperature playing important roles. In this study, Nile tilapia fingerlings (Oreochromis niloticus) weighing an average of 20.00 ± 1.26 g were divided into nine groups (in three replicates). Each group was subjected to different water temperatures (26 °C, 28 °C, and 30 °C) and received one of three dietary protein levels (20%, 25%, and 30%) for two months. Our findings indicate that higher temperatures, particularly at 30 °C, increased water electrical conductivity and total dissolved salts, especially noticeable in fish fed 25% or 30% crude protein (CP). Lower total ammonia nitrogen levels were observed at 28 °C with 25% CP, 30 °C with 30% CP, and 26 °C with 30% CP. Hepatic growth hormone receptor 1 and insulin-like growth factor 1 expression gradually rose with higher dietary CP percentages in fish at 26 °C but declined in those at 30 °C, albeit remaining higher than in the 28 °C groups with 25% CP. Fish at 28 °C showed the best final body weights and growth performance when fed 20% or 25% CP, with no significant difference between these groups. Hepatic leptin expression did not differ significantly among groups, but hepatic fatty acid binding protein expression notably increased in fish fed 30% CP at both 26 °C and 30 °C compared to those at 28 °C with 25% CP. Within the same temperature group, fish fed 30% CP exhibited higher globulin levels, particularly thriving at 28 °C or 30 °C. Hepatic mucin-like protein expression significantly increased across all groups, especially in fish at 30 °C with 30% CP compared to those at 28 °C with 25% CP. Hepatic lysozyme expression also increased notably in fish at 30 °C with 30% CP. Notable changes in superoxide dismutase, catalase, and glutathione peroxidase expression were observed, with the highest serum superoxide dismutase and catalase activities recorded in fish at 30 °C with 25% CP. Overall, dietary protein levels of 25% and 30%, combined with temperatures of 28 °C and 30 °C, yielded favorable outcomes, particularly favoring 28 °C with 25% protein.

Design of an agro-industrial by-products-based media for the production of probiotic bacteria for fish nutrition.

Probiotic production in commercial culture media is expensive, so, it is necessary to design culture media based on "low-cost" components like agro-industrial by-products. Therefore, this study aimed to design an agro-industrial by-product-based culture media using whey, sugarcane molasses, and palm kernel cake as components to produce Lactococcus lactis A12, Priestia megaterium M4, and Priestia sp. M10 isolated from Nile tilapia (Oreochromis niloticus) associated gut microbiota. Higher bacterial concentrations were achieved at high whey concentrations and low concentrations of sugarcane molasses and palm kernel cake (PKC) using agitation. The optimal conditions were whey, 3.84% w/v; sugarcane molasses, 7.39% w/v; PKC, 0.77% w/v; and agitation speed, 75 RPM. Bacterial growth under optimal conditions was compared to that in commercial Brain-Heart Infusion (BHI) broth. L. lactis A12 showed similar growth in the optimal media and BHI. The estimated cost of the culture media based on component prices was USD $ 3.01/L, which is 86.93% lower than BHI broth (USD $ 23.04/L). It was possible to design a "low-cost agro-industrial by-product-based culture media to produce L. lactis A12 and the two Priestia species under monoculture conditions.

Effect of diets containing probiotic yeast Cystobasidium benthicum and fruit Cyrtocarpa edulis on growth and immune parameters of Nile tilapia (Oreochromisniloticus).

This study investigates Cystobasidium benthicum (Cb) probiotic yeast and Cyrtocarpa edulis (Ce) fruit dietary effects, single (0.5 %) or combined (Cb:Ce, 0.25:0.25 %), on growth performance, humoral immunity in serum and skin mucus, and intestinal morphology of Nile tilapia (Oreochromis niloticus) after 14 and 28 days. The Cb group presented the highest (P < 0.05) specific growth rate, weight gain, and absolute growth rate with respect to the control group. Immunological assays indicated that Cb, Ce and Cb:Ce groups increased serum nitric oxide concentration compared to the control group (P < 0.05). Cb and Cb:Ce groups showed the highest serum myeloperoxidase enzyme activity at day 14 and 28, respectively (P < 0.05); whereas, Cb:Ce group had the highest (P < 0.05) myeloperoxidase activity in skin mucus. The superoxide dismutase enzyme activity was unaffected. On day 28, Cb, Ce, and Cb:Ce groups showed higher and lower (P < 0.05) catalase enzyme activity in serum and skin mucus, respectively, compared with the control group. Only the Cb group had higher (P < 0.05) total protein concentration in serum (day 14) and skin mucus (day 14 and 28) with respect to the control group. The lysozyme activity in serum (day 28) and skin mucus (day 14) was higher (P < 0.05) in the Cb group compared to the control group. Only the skin mucus of Ce group showed bactericidal activity against Aeromonas dhakensis (P < 0.05). Histological studies indicated that Cb and Cb:Ce groups increased microvilli height, and Cb, Ce and Cb:Ce augmented goblet cell area at day 14 compared to the control group (P < 0.05). At day 28, microvilli height was higher in all groups and the number of intraepithelial leukocytes increased in Cb and Ce groups with respect to the control group (P < 0.05). The ex vivo assay revealed that A. dhakensis in leukocytes decreased cell viability similar to the control group (P < 0.05). A principal component analysis (PCA) confirmed the results. In conclusion, C. benthicum in the diet was the best supplement to improve the growth and immunity of Nile tilapia.

Assessment of Bacillus species capacity to protect Nile tilapia from A. hydrophila infection and improve growth performance.

The present study evaluated the capacity of three Bacillus species to improve health status and growth performance of Nile Tilapia fed with high levels of soybean meal and challenged with Aeromonas hydrophila. In vitro experiments showed that ß-hemolysin and metalloprotease enzymes were produced by A. hydrophila throughout the exponential growth phase. In vivo experiments showed that 107 colony-forming units (CFUs)/ml of this pathogen killed 50% of control group fishes in 13 days. To evaluate the influence of Bacillus strains on health status and growth performance in Nile Tilapia, 180 fishes (33.44 + 0.05 g) were distributed in 12 tanks of 200 L each, and animals were fed twice per day until satiety. 1) Control group without Bacillus, 2) Bacillus sp1, 3) Bacillus sp2, and 4) Bacillus sp3 groups were formulated containing 106 CFU/g. After 40 days of feeding, the fishes were intraperitoneally injected with 1 ml of A. hydrophila at 2 × 107 CFU/ml, and mortality was recorded. The results showed that cumulative mortality rate was significantly (p< 0.05) lower in the Bacillus sp1 (25%), sp2 (5%), and sp3 (15%) groups, than the control group (50%). Weight gain was also significantly better (p< 0.05) in the Bacillus sp1 (36%), sp2 (67%), and sp3 (55%) groups with respect to the control group (30%). In conclusion, functional diet formulated with high levels of soybean meal and supplemented with Bacillus sp2 could be an alternative to protect Nile tilapia cultures from A. hydrophila infections and improve fish growth performance.

Dietary Pediastrum boryanum microalgal extract improves growth, enhances immunity, and regulates immune-related genes in Nile tilapia.

BACKGROUND: Identifying alternative sustainable feed sources with high nutritional values is crucial for the future of environmentally and socially responsible aquaculture. In this regard, microalgae have been proven to have positive effects on fish health, which overwhelmed our interest in this study. METHODS: Pediastrum boryanum (P. boryanum) was incorporated into Nile tilapia feed at concentrations of 0, 0.75, and 1.5 mg/kg, as control, PbExt0.75, and PbExt1.5 groups to assess its effects on growth and biochemical indices, oxidant/antioxidant activities, immune and stress-related gene expression, and intestinal morphology. RESULTS: After 8 weeks, fish fed P. boryanum supplemented feed exhibited significant increases in final weight, length, condition factor, body weight gain, and specific growth rate, while the spleen-somatic index (SSI) and hepatosomatic index (HSI) showed no significant differences compared to the control group. Dietary P. boryanum supplementation also enhanced IgM levels and lysozyme activity, along with no marked effect on markers of liver function enzymes (alanine aminotransferase/ALT and aspartate aminotransferase/AST) or protein status (total protein and albumin). Furthermore, P. boryanum addition increased the activity of superoxide dismutase (SOD), catalase (CAT), and reduced glutathione (GSH) enzymes, highlighting its antioxidant potential, whereas malondialdehyde (MDA) concentrations showed no significant differences among the groups. Gene expression analysis revealed that tumor necrosis factor-α (TNF-α), interleukin-10 (IL-10), and transforming growth factor-ß1 (TGF-ß1) expression notably increased in groups fed P. boryanum containing feed, while no significant difference was observed in hepatic Heat Shock Protein 70 (HSP70) mRNA expression. Histopathological examination revealed no adverse effects of P. boryanum supplementation on the liver, spleen, or intestinal tissues. Villous height and villous surface area were notably increased in the high P. boryanum supplementation group, suggesting improved intestinal integrity and nutrient absorption. CONCLUSION: Dietary P. boryanum supplementation can potentially improve growth performance, immune response, antioxidant status, and intestinal health of Nile tilapia, making it a promising candidate for sustainable aquaculture.

Growth performance, antioxidant status, intestinal morphology, and body composition of Nile tilapia (Oreochromis niloticus) supplemented with essential oils: A meta-analysis.

This study aimed to evaluate the effects of dietary supplementation with essential oils (EOS) on growth performance, antioxidant status in blood serum, intestinal morphology, and whole-body composition of Nile tilapia (Oreochromis niloticus) through a meta-analytic approach. The search and collection of scientific articles were conducted using the PRISMA methodology, and 45 full-text scientific articles were obtained. The data used in the meta-analysis were extracted from these 45 documents. The effect size was assessed through weighted mean differences (WMD) using Der-Simonian and Laird random effects models. Dietary supplementation with EOS increased (P < 0.001) final weight, body weight gain, specific growth rate, feed intake, protein efficiency ratio, and survival but decreased (P < 0.001) feed conversion ratio. In blood serum, EOS supplementation decreased (P < 0.001) the concentration of malondialdehyde and increased (P < 0.001) the concentration of catalase, superoxide dismutase, and glutathione peroxidase. In the foregut, midgut, and hindgut, greater (P < 0.01) villus height, villus width, and number of goblet cells were observed in response to EOS supplementation. EOS supplementation increased (P < 0.01) crude protein content and decreased (P < 0.05) crude lipid content in the whole-body. In conclusion, essential oils can be used as a dietary additive to improve growth performance, antioxidant status in blood serum, and intestinal morphology in Nile tilapia. Likewise, supplementation with essential oils increases the protein content and decreases the fat content in the whole-body of Nile tilapia.

Dietary nanocomposite of vitamin C and vitamin E enhanced the performance of Nile tilapia.

Nowadays, nanomaterials enter high numbers of daily used products and drug manufacture. A nanocomposite of vitamins C (VC) and vitamin E (VE) with chitosan as a vehicle and protector was used in a comparative eight-week feeding study, Nile tilapia weighing 31.2 ± 0.36 g distributed in seven groups and fed (G1) basal diet, (G2) bulk VC, (G3) VC- nanoparticles (NPs), (G4) bulk VE, (G5) VE-NPs, bulk VCE (G6), and (G7) VC plus VE (VCE)-NPs, respectively. The Nile tilapia-fed nanocomposite vitamins had significantly higher growth performance compared to the control; VCE-NPs had the superiority among tested supplementations where total weight gain (63.6 g), daily weight gain (1.13 g), relative growth rate (206.1%) with lower feed conversion rate (1.6) and insignificant feed intake (101.5 g). Overall, the level of liver enzymes was significantly decreased in fish serum after eight-week nanocomposite supplementation, and dietary VCE-NPs caused a significant reduction of serum AST (18.45 IU/L) and ALT (14.77 IU/L) compared to the control 25.5 IU/L and 17.6 IU/L, respectively. Fish fed dietary VCE-NPs, VC-NPs, and VE-NPs had significant enhancement of RBCs 4.2 × 106/µL, 3.8 × 106/µL, and 3.55 × 106/µL; WBCs 46.15 × 103, 42.9 × 103, and 44 × 103/µL, respectively, Also TP was significantly higher 6.38 g/dL in VCE-NPs group compared to the control and the other treatments. Over all, the dietary nanocomposite vitamins boost the innate immunity of the experimental Nile tilapia, the oxidative burst activity (OBA), phagocytic activity (PA), phagocytic index (PI), and serum antibacterial (SAA) were significantly increased compared to those received bulk vitamins and the control. The activity of antioxidant biomarkers in fish serum including glutathione peroxidase (GPx), catalase (CAT), superoxide dismutase (SOD), total antioxidant capacity (TAC), glutathione reductase (GR), and myeloperoxidase (MPO) showed a rise in the serum of Nile tilapia received nano- and bulk-form of VC and VCE compared to the control and both forms of VE. Furthermore, the level of malondialdehyde (MDA), reduced glutathione (GSH), and oxidized glutathione (GSSG) were significantly increased in the fish serum following the trend of antioxidants enzymes. In conclusion, a dietary nanocomposite of vitamin C and vitamin E enhanced Nile tilapia's growth performance and feed utilization. It could also improve health status and immune response. The values of antioxidant biomarkers indicated that the nanocomposite could help the fish body scavenge the generated reactive oxidative species (ROS).

Comparable to 17α- methyl testosterone, dietary supplements of Tribulus terrestris and Mucuna pruriens promote the development of mono-sex, all-male tilapia fry, growth, survival rate and sex-related genes (Amh, Sox9, Foxl2, Dmrt1).

To evaluate Tribulus terrestris and Mucuna pruriens for inducing all-male tilapia, mixed-sex Nile tilapia, Oreochromis niloticus, (mean weight 0.025 ± 0.009 g; mean length 1.25 ± 0.012 cm), were given a meal supplemented with either T. terrestris powder (commercial fish feed, 40% crude protein) (TT group), M. pruriens seed extract (MP group), MP + TT (mixed group), 17α-methyl testosterone (MT, control positive), or without supplements (control negative). The MP extracts significantly increased (P < 0.05) the final weight, weight gain, weight gain rate, and specific growth rate while feed conversion ratio was significantly decreased (P < 0.05). Plant extracts markedly improved (P < 0.05) the survival rate, proportion of males, and total testosterone compared to control and MT. Estrogen levels were lower in groups with plant extract than other groups. Fifteen days post-feeding, the Amh gene was expressed in the brain of O. niloticus fries with higher levels in MP, TT, and MT groups. Additionally, the expression of the Sox9 and Dmrt1 genes as a male related genes in fish fry gonads revealed significantly (P < 0.05) higher levels in groups fed on MP, TT, and MT compared to control after 30-day post-feeding, whereas; Foxl2 gene expression as a female related gene was significantly (P < 0.05) lower in fish fed on MP, TT, and MT compared to other groups after 30 days post feeding. Histologically, MT, MP, TT, and the mixture all exhibited solely male reproductive traits without noticeable abnormalities. This study concluded that each of the TT or MP extracts can induce sex reversal in tilapia while having no negative health impact compared to MT as the growth and survival rate in the treated groups with TT and MP were higher than control and group treated with MT.

Feeding rates affect growth, metabolism and oxidative status of Nile tilapia rearing in a biofloc system.

The biofloc system is a biotechnology available for fish farming. Feeding rate is an important factor as it influences production costs and fish performance. The aim og this study was to evaluate the effects of feeding rates (2, 4, 6 and 8%) on growth, body composition, biochemical parameters and thiobarbituric acid-reactive-substances in tilapia. An experiment was conducted for 4 weeks, using 144 tilapias juvenile (initial weight = 12.06 ± 0.16 g), in triplicate for feeding rate tested. Fish fed three times a day, with comercial extrude diet (36%CP). After the end of the experiment, measurements were carried out and samples were collected for analysis. The feeding rate of 6% increased fish growth parameters, not differing between 4 and 8%. Since apparent feed conversion increased proportionally to increase in feed supply. Body protein of fish was higher at 8% feeding rate and the dry matter raised according to the rate. The feeding rates affected the body lipids in fish. Fish that fed 6% and 8% showed more lipid in the whole body. The biochemical parameters presented a lower amount of protein, amino acids, and hepatic glucose when employing a feed rate of 6%. Higher levels of ammonia were observed in the muscle of fish reared at 4% of feeding rate. There was no difference in amino acids and ammonia regarding the gills. Fish reared at lower feeding rates (2% and 4%) showed better oxidative parameters, which may be due to the consumption of the biofloc phenolic compounds. We recommend the use of a 4% feeding rate for juvenile tilapia in a Biofloc Technology system.

Antioxidant and antibacterial efficiency of the ethanolic leaf extract of Kratom (Mitragyna speciosa (Korth.) Havil) and its effects on growth, health, and disease resistance against Edwardsiella tarda infection in Nile tilapia (Oreochromis niloticus).

The research examined the impact of an ethanolic extract from the leaves of Kratom (Mitragyna speciosa (Korth.) Havil.) on the growth, antioxidant capacity, immune-related gene expression, and resistance to disease caused by Edwardsiella tarda in Nile tilapia (Oreochromis niloticus). The findings revealed that the extract had the important phytochemical content in the extract included total phenolics content, total flavonoids content, vitamin C, and total antioxidant capacity and 5.42 % of the crude extract was mitragynine. The extract demonstrated antioxidant activity, as evidenced by its IC50 values against ABTS and DPPH radicals and its ferric reducing power in vitro. Moreover, the MIC-IC50 value of 0.625 mg/mL indicated that the growth of the bacteria was reduced by approximately 50 %, and the MBC was 2.50 mg/mL against E. tarda. Furthermore, the orally administered Kratom leaf extract to fingerling tilapia for 8 weeks exhibited a noticeable increase in oxidative stress, as demonstrated by the increase in MDA production in the 10 and 25 g/kg groups. It also exhibited an increase in acetylcholinesterase (AChE) activity in muscle tissue at the 50 g/kg group. However, when administered at a feeding rate of 5-10 g/kg feed, the extract showed an increase in the expression of immune-related genes (IL1, IL6, IL8, NF-kB, IFNγ, TNFα, Mx, CC-chemokine, CD4, TCRß, MHC-IIß, IgM, IgT, IgD) and enhanced resistance to E. tarda infection in fish. Conversely, administering the extract at 25-50 g/kg feed resulted in contrasting effects, suppressing and reducing the observed parameters. Nevertheless, feeding the extract at all concentrations for 8 weeks did not produce any changes in the histology or systemic functioning of the liver and intestines, as indicated by blood biochemistry. These findings suggest that the ethanolic leaf extract from Kratom has the potential to be used as a substitute for antibiotics in the management of bacterial infections in Nile tilapia culture, with a recommended dosage of 5-10 g/kg feed/day for a maximum of 8 weeks.

Dietary algal-sourced zinc nanoparticles promote growth performance, intestinal integrity, and immune response of Nile tilapia (Oreochromis niloticus).

BACKGROUND: Trace elements play a crucial role in fish nutrition, with zinc (Zn) being one of the most important elements. BIO-sourced zinc nanoparticles were synthesized using the green microalga Pediastrum boryanum (BIO-ZnNPs, 29.35 nm). 30 or 60 mg/ kg dry feed of the BIO-ZnNPs (BIO-ZnNPs30 and BIO-ZnNPs60) were mixed with the Nile tilapia (Oreochromis niloticus) basal diet and fed to the fish for 8 weeks to evaluate their impact on fish growth, digestion, intestinal integrity, antioxidative status, and immunity. RESULTS: A significant enhancement was observed in all investigated parameters, except for the serum protein profile. BIO-ZnNPs at 60 mg/kg feed elevated the activities of reduced glutathione (GSH) and catalase (CAT), enzymatic antioxidants, but did not induce oxidative stress as reflected by no change in MDA level. Fish intestinal immunity was improved in a dose-dependent manner, in terms of improved morphometry and a higher count of acid mucin-producing goblet cells. Interleukin-8 (IL-8) was upregulated in BIO-ZnNPs30 compared to BIO-ZnNPs60 and control fish groups, while no significant expressions were noted in tumor necrosis factor-alpha (TNFα), nuclear factor kappa B (NFkB), and Caspase3 genes. CONCLUSION: Overall, BIO-ZnNPs inclusion at 60 mg/kg feed showed the most advantage in different scenarios, compared to BIO-ZnNPs at 30 mg/kg feed. The positive effects on growth and intestinal health suggest that BIO-ZnNPs supplementation of aquafeeds has many benefits for farmed fish.

Arthrospira platensis nanoparticles dietary supplementation improves growth performance, steroid hormone balance, and reproductive productivity of Nile tilapia (Oreochromis niloticus) broodstock.

This study evaluates the impact of dietary supplementation of the blue-green alga Arthrospira platensis NIOF17/003 nanoparticles (AN) on the growth performance, whole-body biochemical compositions, blood biochemistry, steroid hormonal, and fry production efficiency of Nile tilapia (Oreochromis niloticus) broodstock, during the spawning season. After a 21-day preparation period to equip the females and ensure that their ovaries were filled with eggs, mating between the mature females and males took place in a 3:1 ratio during a 14-day spawning cycle. A total of 384 tilapia broodstock 288 females and 96 males with an initial body weight of 450.53±0.75, were divided into four groups; AN0: a basal diet as a control group with no supplementation of Arthrospira platensis, and the other three groups (AN2, AN4, and AN6) were diets supplemented with nanoparticles of A. platensis at levels of 2, 4, and 6 g kg─1 diet, respectively. The results found that fish-fed group AN6 showed the highest significant differences in weight gain (WG), final weight (FW), feed conversion ratio (FCR), protein efficiency ratio (PER), and feed efficiency ratio (FER). Females fed the AN6 diet showed the highest significant fat content. Compared to the AN0 group, fish fed on the supplemented diets showed significant improvement (p < 0.05) in triglyceride, glucose, and aspartate aminotransferase (AST). A gradual increase in AN inclusion level resulted in a gradual increase in the concentrations of luteinizing hormone (LH), and follicle-stimulating hormone (FSH), testosterone, progesterone, and prolactin. The rates (%) of increase in fry production for females fed supplemented diets were 10.5, 18.6, and 32.2% for AN2, AN4, and AN6, respectively, compared to the control group. This work concluded that the inclusion levels of 6 g kg─1 of A. platensis nanoparticles in the diet of Nile tilapia broodstock significantly improved the growth performances, steroid hormone concentrations, and increased the fry production efficiency by 32.2%, respectively. These findings revealed that A. platensis nanoparticles resulted in a significantly enhanced female' reproductive productivity of Nile tilapia broodstock.

Pichia kudriavzevii as feed additive in Nile tilapia (Oreochromis niloticus) diet.

Yeasts are unicellular eukaryotic microorganisms extensively employed in various applications, notably as an alternative source of protein in feeds, owing to their nutritional benefits. Despite their potential, marine and mangrove yeast species used in the aquaculture industry have received little attention in the Philippines. Pichia kudriavzevii (A2B R1 ISO 3), sourced from bark samples, was selected and mass-produced due to its high protein content and amino acid profile. The dried biomass of P. kudriavzevii was incorporated into the diets of Nile tilapia (Oreochromis niloticus) juveniles at varying inclusion levels (0, 1, 2, and 4 g/kg diet) and its effect on their growth performance, body composition, and liver and intestinal morphology was assessed after 40 days of feeding. The groups that received P. kudriavzevii at a concentration of 2 g/kg diet exhibited higher final body weight, percent weight gain, and specific growth rate in comparison to the other treatment groups. Whole body proximate composition did not vary among the dietary groups. Intestinal and liver histopathology also indicated no abnormalities. These findings suggest the potential of ascomycetous P. kudriavzevii as a beneficial feed additive in Nile tilapia diets, warranting further investigation into its long-term effects and broader applications in fish culture.

Screening and effects of intestinal probiotics on growth performance, gut health, immunity, and disease resistance of Nile tilapia (Oreochromis niloticus) against Streptococcus agalactiae.

In the present study, 59 autochthonous bacteria were isolated from the intestine of tilapia. Following enzyme producing activity, antagonistic ability, hemolytic activity, drug sensitivity assessments, and in vivo safety evaluation, 7 potential probiotic strains were screened out: Bacillus tequilensis BT0825-2 (BT), Bacillus aryabhattai BA0829-3 (BA1), Bacillus megaterium BM0505-6 (BM), Bacillus velezensis BV0505-11 (BV), Bacillus licheniformis BL0505-18 (BL), B. aryabhattai BA0505-19 (BA2), and Lactococcus lactis LL0306-15 (LL). Subsequently, tilapia were fed basal diets (CT) and basal diets supplemented with 108 CFU/g of BT, BA1, BM, BV, BL, BA2 and LL, respectively. After 56 days of continuous feeding, the growth parameters (weight gain, final weight, and specific growth rate) showed significant improvement (p < 0.05) in both BM and BA2 groups. The total cholesterol and triglycerides of serum were significantly decreased in BV and LL groups (p < 0.05). The superoxide dismutase, glutathione reductase, and lysozyme of BV, BA2 and LL groups were increased, and the malondialdehyde of BV group was significantly decreased. The villous height and amylase of midgut were increased in BV, BA2 and LL groups. In addition, the expression levels of ZO-1 and occludin genes in the midgut of tilapia were enhanced in BM, BV, BA2 and LL groups. The supplementation of probiotics reduced the abundance of Cyanobacteria and increased the abundance of Actinobacteria at the phylum level. At the genus level, the addition of probiotics increased the abundance of Romboutsia. Furthermore, improvement in the expression of immune-related genes were observed, including interleukin 1ß, interleukin 10, tumor necrosis factor alpha, and transforming growth factor beta (p < 0.05). After challenging with S. agalactiae, the survival rates of BV, BA2 and LL groups were significantly higher than CT group (p < 0.05). Above results indicated that BM, BA2, BV and LL improved growth performance, gut health or immunity of tilapia, which can be applied in tilapia aquaculture.

Replacing soybean meal with fermented rapeseed meal in diets: potential effects on growth performance, antioxidant capacity, and liver and intestinal health of juvenile tilapia (Oreochromis niloticus).

This study aims to evaluate the effects of substituting soybean meal with fermented rapeseed meal (FRM) on growth, antioxidant capacity, and liver and intestinal health of the genetically improved farmed tilapia (GIFT, Oreochromis niloticus). A total of 450 tilapia (7.22 ± 0.15 g) were fed with five experimental diets, including a basal diet containing 40% soybean meal (CP0), which was subsequently replaced by 25% (CP25), 50% (CP50), 75% (CP75), and 100% (CP100) FRM in a recirculated aquiculture system for 9 weeks (30 fish per tank in triplicates). The results showed that the weight gain, specific growth rate, feed intake, feed efficiency, hepatosomatic index, and viscerosomatic index of fish in both CP75 and CP100 groups were significantly lower than those in CP0 group (P < 0.05). The fish in CP100 group had the lower content of muscle crude protein while the higher level of muscle crude lipid (P < 0.05). Activities of serum aspartate aminotransferase, alanine aminotransferase along with total triglyceride in CP100 group were significantly higher than those in CP0 group (P < 0.05). There were no significant differences in the contents of liver protease, amylase, and lipase among five groups (P > 0.05). The activities of liver total antioxidant capacity and superoxide dismutase exhibited the increased tendency with the increase of FRM replacement levels from 25 to 50% (P < 0.05), while then significantly decreased from 75 to 100% (P < 0.05). Histological morphology indicated that the fish in between CP75 and CP100 groups had poor liver and intestine health. Intestinal microbial diversity analysis showed that the relative abundance of Cetobacterium and Alcaligenaceae in both CP75 and CP100 groups were lower than that in other three groups. In conclusion, the maximum replacement level of soybean meal with FRM in the diet was determined to be 50% without compromising the growth performance, antioxidant status, and liver and intestinal health of tilapia under the current experimental conditions. The observed decrease in food intake and subsequent retarded growth performance in the CP75 and CP100 groups can be attributed directly to a reduction in feed palatability caused by FRM.

Ontogeny of daily rhythms in the expression of metabolic factors in Nile tilapia (Oreochromis niloticus) kept at two different temperature regimes: Thermocycle and constant temperature.

The daily variations of temperature are one of the main synchronizers of the circadian rhythms. In addition, water temperature influences the embryonic and larval development of fish and directly affects their metabolic processes. The application of thermocycles to fish larvae has been reported to improve growth and the maturation of the digestive system, but their effects on metabolism are poorly understood. The aim of the present study was to evaluate the effect of two different temperature regimes, cycling versus constant, on the daily rhythms of metabolic factors of Nile tilapia (Oreochromis niloticus) larvae. For this purpose, fertilized eggs were divided into two groups: one reared in a 31 °C:25 °C day:night thermocycle (TCY) and another group maintained in a constant 28 °C temperature (CTE). The photoperiod was set to a 12:12 h light/dark cycle. Samples were collected every 4 h during a 24-h cycle on days 4, 8 and 13 post fertilization (dpf). The expression levels of alanine aminotransferase (alt), aspartate aminotransferase (ast), malic enzyme, glucose-6-phosphate dehydrogenase (g6pd), phosphofructokinase (pfk) and pyruvate kinase (pk) were analyzed by qPCR. Results showed that, in 13 dpf animals, most of the genes analyzed (alt, ast, malic, g6pd and pfk) showed daily rhythms in TCY, but not in the group kept at constant temperature, with most acrophases detected during the feeding period. An increase in nutrient metabolism around feeding time can improve food utilization and thus increase larval performance. Therefore, the use of thermocycles is recommended for tilapia larviculture.

Investigating the optimum stocking density of tilapia (Oreochromis niloticus) for intensive production focused to in-pond raceway system.

The primary objective of this trial was to study the effects of stress caused by stocking density in tilapia (Oreochromis niloticus) cultured in the in-pond raceway system (IPRS). Fingerlings (Initial body weight = 30.00 ± 1.20 g) were reared at different stocking densities i.e. low stocking density (n = 13,000; 1.77 kg/m3), medium stocking density (MSD) (n = 17,000; 2.32 kg/m3), and high stocking density (HSD) (n = 21,000; 2.86 kg/m3), all confined within the raceways of the IPRS. Each group was studied in triplicates. The observed growth revealed a regression in the HSD treatment, evident in its reduced weight gain per fish per day, in contrast to other treatments. Survival rate across all treatments was above 99%. Notably, the HSD treatment exhibited an elevated level of cortisol; however, this intensified crowding stress did not significantly undermine the nutritional value of the fish in HSD and other experimental treatments. Furthermore, an elevation in the levels of superoxide dismutase, catalase, and glutathione peroxidase was noted within the HSD treatment in comparison to the other treatments to reduce the damage caused by reactive oxygen species. As the trial proceeded, functions of digestive enzymes like amylase, protease, and lipase diminished consistently across all treatments. This could possibly signify a deliberate redirection of energy resources toward stress alleviation rather than the usual digestive processes. In summation, it can be reasonably deduced that a stocking density of approximately 2.32 kg/m3 (MSD) emerges as the optimal threshold for effectively cultivating tilapia within an intensive aquaculture framework.