Catfish Diets Research Articles

Effects of Substituting Soybean Meal With Winged Bean on Growth, Physiological Function and Flesh Quality of Indian Butter Catfish (Ompok bimaculatus).

Soybean meal (SBM) remains a primary protein source in aquafeeds. This study investigated the potential of winged bean (Psophocarpus tetragonolobus) meal as a SBM replacement in diets for butter catfish (Ompok bimaculatus) juveniles (mean weight: 1.24 ± 0.23 g). A response surface methodology (RSM) optimized processing conditions to minimize antinutritional factors (ANFs) in winged bean meal (WBM), resulting in minimized tannin (4.14 ± 0.018 mg/g at 40 min, 110°C), phytate (0.414 ± 0.0009 mg/g at 31.67 min, 104.5°C) and trypsin inhibitor activity (70.8 ± 0.06% inhibition at 20 min, 90°C). Experimental diets containing 30% crude protein and varying levels of WBM substitution (0%, 25%, 50%, 75% and 100%) were fed for 70 days. Growth performance, measured by weight gain, was significantly higher in the 25% substitution group (p < 0.05) but not significantly different from the control at 50% substitution. Quadratic regression analysis predicted an optimal inclusion level of 15.10% for maximizing weight gain. Survival rates did not differ significantly among treatments (p > 0.05). Feed utilization was most efficient in the 25% substitution group. Haematological and immunological parameters indicated improved fish health at the 25% substitution level. Flesh quality attributes, including texture profile analysis, pH and antioxidant activity, were superior in the 25% group compared to other treatments. However, colour enhancement was more pronounced at higher inclusion levels (≥50%). While flesh pH and antioxidant activity suggested potential stress at higher winged bean inclusion levels, the 25% group showed improved values compared to the control. These findings suggest that WBM can potentially replace up to 50% of SBM in butter catfish diets, offering a promising alternative protein source. This study provides preliminary data on the feasibility and prospects of utilizing WBM in O. bimaculatus diets.

Effects of plant oil extracts on the digestibility, hematobiochemistry, and hematology of Clarias gariepinus

BackgroundPlant oil extract like sesame oil has high polyunsaturated fatty acids, while palm oil extracts are saturated. A serial substitution of crude sesame extract together with crude palm extract was used in novel diets of African catfish. Five types of feeds designated as feed F1 to feed F5 were made to vary in the inclusion of crude sesame extract (CSE) and crude palm extract (CPE), CSE: CPE), as follows: F1, 25:5, F2, 20:10, F3, 15:15, F4, 10:5, and F5, 5:25. Feed F6 was a commercial feed. The fish were fed to satiation for 70 days. We analyzed the digestibility of CSE, CPE, the feeds and the hematology and hematobiochemical parameters of the catfish.ResultsResults showed that the catfish had significantly higher digestibility for CSE 93.34 ± 0.22% than for CPE 78.98 ± 0.11%. Feed F1 had the highest digestibility 91.32 ± 0.07%, followed by feed F2, 82.25 ± 0.04%. The higher digestibility of feeds F1, F2, and F3 than F4 and F5 could be due to the lipids and fatty acid composition of the feed. Sesame seed is known to be high in phospholipids and triacylglycerols, and this enhances digestibility. Phospholipids are present in low quantities in palm oil. Crude sesame extract reduced blood cholesterol, triglycerides, and glucose, while crude palm extract increased them. Conversely higher dietary inclusions of CSE (F1 > F2 > F3) in that order increased the Hb, RBC, MCH, MCHC, TWBC, and the PCV.aConclusionsCrude sesame extract should be added to the diets of African catfish for optimal digestibility and enhanced hematobiochemical and hematological indices. Crude palm extract should be added but not above 10% for optimal performances.

Evaluation of the potential probiotic Bacillus subtilis isolated from darkbarbel catfish (Pelteobagrus fulvidraco) on growth performance, serum immunity, and disease resistance of Aeromonas hydrophila.

This study aimed to identify potential probiotic strains of Bacillus subtilis from healthy fish gut microbiota for application in aquaculture. The effects of dietary B. subtilis administration on growth performance, serum enzyme activity, immune gene expression, and disease resistance in darkbarbel catfish (Pelteobagrus fulvidraco) were investigated. The isolate, identified through gene sequencing and biochemical tests, demonstrated resilience to pH 3.0% and 6.0% bile, and exhibited extracellular protease, cellulose, lipase, and amylase production. Darkbarbel catfish were fed diets with varying B. subtilis concentrations (0 CFU/kg [T0], 107 CFU/kg [T1], 108 CFU/kg [T2], and 109 CFU/kg [T3]). After 8 weeks, significant increases (p < 0.05) were observed in final body weight, weight gain rate, specific growth rate, serum lysozyme, serum superoxide dismutase, alkaline phosphatase, and total antioxidant capacity, whereas malondialdehyde levels significantly decreased. Feeding darkbarbel catfish with B. subtilis diets increased immunoglobulin M (IgM) and C3 gene expression (p < 0.05), indicating a positive impact on the fish's immune system. The strain upregulated interleukin 10 (IL-10) and transforming growth factor-β (TGF-β) expression and downregulated TNF-α and IL-1β, suggesting potential anti-inflammatory effects. Following a 7-day challenge with Aeromonas hydrophila, fish fed with B. subtilis exhibited lower mortality, with higher survival rates in the T2 and T3 groups. In conclusion, supplementing darkbarbel catfish diets with B. subtilis effectively enhances growth performance, immune response, and disease resistance.

Effects of dietary inclusion of Chaya leaf (Cnidoscolus chayamansa) meal as feed additives in the diets of African catfish (Clarias gariepinus, Burchell, 1822) Juveniles

Effects of dietary inclusion of Chaya leaf (Cnidoscolus chayamansa) meal as feed additives in the diets of African catfish (Clarias gariepinus, Burchell, 1822) Juveniles

The synergistic effects of dietary protein and stocking density on performance, digestive enzymes, and hemato-biochemistry parameters of juvenile striped catfish (Pangasianodon hypophthalmus)

This experiment was designed to examine the impacts of different dietary protein levels (DPLs) and their interaction on the growth and some physiological indices of juvenile striped catfish, Pangasianodon hypophthalmus, reared at different stocking densities (SDs) for 15 weeks. A total of 1440 striped catfish (initial weight = 10.0 ± 2.2 g) were randomly allocated into six equal treated groups (three replicates per treated group). Fish were fed two DPLs of 25 % and 30 % and reared under different SDs of 20, 40, and 60 fish/m3. The obtained results indicated that with increasing DPL, growth parameters, and digestive enzyme activities, the liver function enzyme activities, serum protein constituents' levels, and concentrations of thyroid hormones significantly increased, while levels of serum glucose, total cholesterol, and triglycerides remarkably decreased. On the other hand, increasing SD negatively affects growth, digestive and liver enzyme activities, some hematological parameters, and fish-body chemical analysis. The interaction between DPLs and different SDs significantly improved the most estimated parameters with increasing DPLs despite intensifying SDs. In general, afforded striped catfish diets containing 30 % DPL and stocked at 20 fish/m3 presented the best performance, consumed feed efficiency, and health status. Thus, the interaction between DPLs and SDs demonstrated the favorable benefits of increasing DPLs by diminishing some of the adverse impacts generated by high SDs, which may subsequently lead to high production and increased revenues for fish farmers.

Dietary supplementation of mineral nanoparticles for channel catfish (Ictalurus punctatus).

This study evaluated the supplementation of iron and copper nanoparticles in channel catfish diets and their influences on growth and health. A comparative feeding trial was carried out for 9weeks to evaluate combinations of iron and copper nanoparticles: only iron nanoparticles (IronNP), only copper nanoparticles (CopperNP), CopperNP + IronNP, and a control diet supplemented with inorganic iron and copper (FeSO4 and CuSO4). After a 9-week feeding trial, growth performance, hematological parameters, whole-body proximate composition, and intestinal microbiota were evaluated, and fish were subjected to a bacterial challenge against Edwardsiella ictaluri to evaluate the contribution of the experimental treatments to fish health status. No statistical differences were detected for catfish fed the various diets in terms of production performance or survival after bacterial challenge. The hematocrit and RBC counts from fish fed the diet containing copper nanoparticles were significantly lower than the control group. A higher relative abundance of gram-positive bacteria was found in the digesta of catfish fed diets containing copper nanoparticles. Furthermore, in the context of hematology, iron nanoparticles did not impact the blood parameters of channel catfish; however, reduced hematocrits were observed in fish fed the copper nanoparticle diet, which lacked supplemental dietary iron, thus reinforcing the importance of dietary iron to catfish hematopoiesis. Nonetheless, additional studies are needed to investigate the effects of dietary copper nanoparticle supplementation in catfish diets to better illuminate its effects on the intestinal microbiota.

Co-incorporation of Black Soldier Fly (Hermetia illucens) Larvae and Moringa (Moringa oleifera) Leaves in the Diet Increase African Catfish Profitability (Clarias gariepinus)

Aquaculture is a fast-growing activity in Cameroon and required substantial quantities of affordable protein-rich feed. In this study, we co-incorporated Moringa leaves (MOL) and black soldier fly larvae meal (BSFLM) in catfish diet, and the effect was evaluated on feed floatation, fish growth, flesh organoleptic qualities and profitability. 450 juvenile`s catfish weighing averagely 10 g, were subjected to five dietary treatments consisting of: T0 (0% BSFLM and 0% MOL); T1 (6.25% BSFLM and 5% MOL); T2 (12.5% BSFLM and 10% MOL); T3 (18.75% BSFLM and 15% MOL) and T4 (25% BSFLM and 20% MOL) for 119 days. The treatment T3 containing 18.75% BSFLM and 15% MOL recorded the highest floatation duration, fish weight (113.83±17.31 g) and weight gain (103.25±17.8 g), and the lowest feed conversion ratio (1.60±0.37). The flesh tasted good and was acceptable in all treatments. Incorporating BSFLM and MOL in the diets reduced the cost per kg of feed from 18 to 23%, thus increasing the system's profitability from 45.91 to 60.84%. We concluded that BSFLM and MOL can partially substitute fish meal in catfish diet and improve the profitability and offers insights into the development more profitable and sustainable aquaculture in Cameroon and globally.

Dietary inclusion of insect oil: Impact on growth, nutrient utilisation, lipid metabolism, antioxidant and immune-related responses in European catfish (Silurus glanis L)

In this study, we investigated the black soldier fly (Hermetia illucens) larvae oil (IO) as replacement of fish oil and vegetable oil in the diets of European catfish. The formulated diets included a control diet (CTR) containing fish oil (FO) and rapeseed oil (RO), and two experimental diets replacing FO and RO, with 50% and 100% IO, respectively. The nutritional trial comprising 630 European catfish juveniles (average initial body weight: 28.1 ± 0.17 g) randomly distributed into triplicated dietary groups (CTR, IO50, and IO100) was conducted for 8 weeks in a recirculation aquaculture system. The study was focused to evaluate the impact of IO on fish growth and nutrient utilisation, lipid metabolism, antioxidant, and immune-related responses in juvenile fish. Results obtained indicated that all the diets promoted adequate fish growth and feed utilisation, with no significant differences in these parameters between the dietary fish groups. It appears that the diets did not impact the activity of digestive enzymes, but a decrease in the apparent digestibility coefficients was observed. Significant differences were observed in tissue fatty acid (FA) composition. The significantly higher levels of whole-body total saturated fatty acids and arachidonic acid in fish fed IO-based diets relative to those fed CTR diet were accompanied by significantly lower levels of whole-body monounsaturated fatty acids and n-3 polyunsaturated fatty acids (n-3 PUFA). However, some deviations in this trend were observed in the liver highlighting the sparing effect for long chain polyunsaturated fatty acids (LC-PUFAs). Gene expression analysis showed a significant upregulation of genes encoding lipoprotein lipase (lpl), carnitine palmitoyl transferase (cpt1a), and hepatocyte nuclear factor 4 alpha (hnf4α) in the livers of fish fed the IO100 diet. Among the five immune-related genes examined in the spleen, only interferon regulatory factor 1 was significantly upregulated in fish fed IO50 relative to the CTR. These results indicated upregulated metabolic activities in fish fed the IO100 diet probably due to a higher level of dietary medium chain saturated fatty acids (MCSFA) and a lower level of LC-PUFA, creating the need for fish to oxidise more MCSFA and to deposit more LC-PUFA in the tissues in order to maintain fatty acid balance.

Potential effects of Sargassum kjellmanianum as a dietary supplement on the growth performance, immunity response, antioxidant status, and ammonia resistance of yellow catfish (Pelteobagrus fulvidraco)

This study aimed to investigate the potential effects of seaweed Sargassum kjellmanianum (SK) as a dietary supplement on the growth performance, blood biochemistry, immunology, antioxidants, and ammonia stress resistance of yellow catfish, Pelteobagrus fulvidraco. Four diets containing 0 % SK (control), 2.5 % SK, 5 % SK, and 10 % SK were fed to fish for 8 weeks. After the feeding trial, the fish were exposed to ammonia for 72 h and their mortality was recorded. Compared with the control group, the growth performance was significantly increased in the 2.5 % and 5 % SK groups (P < 0.05). Serum albumin levels were significantly increased (P < 0.05), meanwhile serum aspartate aminotransferase (AST), alanine aminotransferase (ALT), total cholesterol, triglyceride, and low-density lipoprotein cholesterol levels were significantly decreased in fish fed with 2.5 % and 5 % SK (P < 0.05). Interestingly, the serum AST and ALT activities were significantly increased in the 10 % SK group (P < 0.05). Additionally, serum lysozyme, acid phosphatase, and complement 4 levels were all significantly increased in all SK groups than those of the control group (P < 0.05). In addition, serum malondialdehyde levels were significantly decreased (P < 0.05). Meanwhile, the total antioxidant capacity, superoxide dismutase, and catalase levels were significantly increased in the 2.5 % and 5 % SK groups with relative to the control group (P < 0.05). Notably, the cumulative mortality rate was significantly higher (46.67 %) in the control fish than those fed the SK diets (35–38.33 %) (P < 0.05). Taken together, the results indicated that adding SK to the diet of yellow catfish can enhance growth performance, stimulate immune responses, improve antioxidant status, and increase resistance to ammonia stress. It is recommended to use concentrations between 2.5 % and 5.0 % in present study.

Maintenance requirement and growth utilization efficiency of digestible methionine and cysteine determined for striped catfish (Pangasianodon hypophthalmus) using ration level technique

Knowledge of the amino acid (AA) requirements for striped catfish (Pangasianodon hypophthalmus) is very limited. The main objective of the study was to determine maintenance requirements and utilization of digestible methonine (Met) and other essential amino acids (EAA) for growth in juvenile striped catfish. To evaluate the objective, a series of three different trials were carried out. Initially, a 28-d feed deprivation study showed an allometric relationship between energy, protein, or AA losses (y) and geometric body weight (BW), where the relationship was expressed as a power function (y = aBWb) with the exponent values (b) being 0.84 for energy, 0.83 for protein, and 0.81–0.90 for various EAAs. Next, a digestibility trial was carried out to determine apparent digestibility coefficients of energy, protein and AA from the ingredients, including: fish meal, soybean meal, wheat bran, regular and defatted rice bran. These values were then used in the final trial to formulate two diets on a digestible AA basis with similar crude protein (31%), energy (17.1 kJ g−1) and AA composition - except for digestible Met and Met+Cys, which were 0.47% and 0.90% for Diet A, and 0.61% and 1.05% for Diet B. The diets were fed to quadruplicate groups of fish (∼10 g initial weight; 20 fish per tank) at increasing ration levels (∼ 35%, 55%, 77%, 93% and 100% apparent satiation) for 64 days. One group was deprived of feed for 28 days. The results showed that feeding catfish at increasing ration levels significantly improves the growth performance in both dietary treatments. Additionally, the group fed Diet B showed significantly better weight gain than the corresponding group fed Diet A at 93% and 100% satiation. The maintenance requirement was determined to be 21.77 mg digestible (dig) Met kg−0.83 d−1 and 35.3 mg dig Met+Cys kg−0.83 d−1 based on a linear model and to be 18.8 mg digestible (dig) Met kg−0.83 d−1 and 30.7 mg dig Met+Cys kg−0.83 d−1 based on an exponential fit to the data. The efficiency of digestible Met utilization (kDMetassessed based on Diet B) for growth above maintenance was found to be 63% (including data of all ration levels) or 71% (excluding data of 100% satiation), while that for the Met+Cys (kDM+C) was found to be 46% (including data of all ration levels) or 51% (excluding data of 100% satiation). The efficiency of digestible protein utilization for weight gain with Diet B was found to be higher (66%) than that with Diet A (57%), indicating the importance of balancing striped catfish diets for dietary Met. The study also determined maintenance requirements and utilization efficiency of other EAAs which need to be further improved. These data can be used to derive AA requirements for striped catfish based on a factorial modelling approach which relies on maintenance requirements, growth utilization of AA, and targeted growth or protein deposition.

Unravelling a specialised diet of an Amazonian catfish in a controlled flood-pulse area by combining stomach-content and stable-isotope analyses

Context Hydrological dynamics are crucial in fish ecology. Aims To evaluate the effect of the flood pulse on the feeding ecology of Doras higuchii in the reduced-flow section of the Belo Monte dam, Xingu River, Brazil. Methods Collections were conducted between December 2020 and November 2021. The fish were measured and had their stomachs removed. Muscle tissue was also extracted for stable-isotope analysis. Stomach contents were inspected to assess diet, testing the influence of hydrological periods by using GLM. In addition, we evaluated the effect of the flood pulse on the δ13C and isotopic ratios of individuals Results In total, 362 specimens of D. higuchii were analysed, highlighting a diet mainly on the basis of sediment (74.9%) and aquatic insects (24.8%), not varying between periods characterising the species as a specialist for having detritivorous habit, as well as the extension of the trophic niche. There was variation in food intensity, with higher average food consumption in the flood period. The isotopic composition (δ13C and δ15N) also did not differ between periods. Finally, δ15N did not vary by length class. Conclusions This information helps understand the interface between environmental and biological factors in an environment affected by a hydroelectric dam. Implications Our results may help fill gaps in knowledge about the diet of doradid fishes.

Effects of three short-chain fatty acids on growth, intestinal microbiota composition, and ammonia tolerance of juvenile yellow catfish Pelteobagrus fulvidraco

The objective of this research was to examine how the growth, ammonia tolerance, and intestinal microbiota composition of juvenile yellow catfish are affected by dietary supplementation of isobutyric acid (IBA), isovaleric acid (IVA), and 2-methylbutyric acid (2-MBA). During the 8-week trial, four groups were fed the basal diet (Control), and the basal diet supplementation with 0.25% IBA, IVA and 2-MBA, respectively. The research shows that the yellow catfish in the IBA and 2-MBA groups had a higher weight gain rate and specific growth rate than the control group, but feed conversion ratio has the opposite trend. Dietary supplementation of IBA and 2-MBA can significantly improve digestive enzymes activities (α-amylase, lipase, and trypsin) in intestinal tract and blood health (serum albumin increased, alanine transaminase and aspartate transaminase decreased). The up-regulation of IGF-1, Myod, and MyoG gene mRNA expression levels occurred significantly in the muscle tissue of the IBA, IVA, and 2-MBA groups, but IL 1 and IL8 genes in intestinal tract were significantly down-regulated. Supplementation of IBA, IVA and 2-MBA significantly increased the relative abundance of Candidatus Arthromitus, while decreased the relative abundance of Achromobacter, most notably in IBA group. After 96-h ammonia stress, cumulative mortality in IBA group was the lowest. Supplementing the diet of yellow catfish with IBA or 2-MBA can enhance their growth, digestive enzyme activity, and blood health status. Additionally, IBA can improve ammonia tolerance, which may be related to the increase abundance of Candidatus Arthromitus in intestine.

Exploring the nutritional value of corn fermented protein as a replacement for soybean meal in diets for juvenile channel catfish (Ictalurus punctatus): Impacts on production performance, intestinal health, and disease resistance

The use of corn fermented protein (CFP) can be a promising alternative ingredient to replace soybean meal (SBM) in aquafeeds, because of its attractive price and constant supply. In this study, the apparent digestibility of CFP was evaluated with channel catfish (Ictalurus punctatus), followed by a comparative feeding trial in which dehulled, solvent extracted SBM in the control diet was incrementally replaced with graded levels of CFP. A slight but significantly higher apparent protein digestibility coefficient was observed for SBM (91%) compared to CFP (89%). However, phosphorus and lipid were twice as available from CFP than SBM. A 60-day feeding trial was conducted, testing the gradual replacement of SBM by CFP on an equalnitrogen basis at 0, 25, 50, 75, and 100%. Channel catfish juveniles (∼11.6 g) were stocked in 30 aquaria (30 fish/ 110-L tank; n = 6) operating as a recirculating system and offered the experimental diets to apparent satiation twice daily. No differences were observed for hepatosomatic index, survival, or serum superoxide dismutase and lysozyme activities. Also, no treatment effects were observed for whole-body protein, ash, and protein conversion efficiency. However, weight gain, feed efficiency, intraperitoneal fat, and whole-body lipid were significantly affected by the dietary treatments with CFP able to replace up to 40 to 58% of the SBM in the diet while providing similar fish performance and body composition as fish fed the control diet. Digesta samples from the posterior segment of the intestine were subjected to DNA extraction, followed by 16S rRNA gene (V3-V4 region) sequencing to profile the intestinal microbiota. A higher relative abundance of Aeromonas spp. was observed for fish fed the control diet. The remaining fish from the feeding trial were challenged with Edwardsiella ictaluri, and cumulative survival was monitored for 21 days. Survival after the bacterial challenge gradually increased as the inclusion levels of CFP increased in the diets, with the 100% replacement treatment being significantly different from the control diet. In conclusion, CFP is a promising alternative plant protein ingredient with high protein and phosphorus digestibility, and it can replace up to 40 to 58% of the SBM in feed formulations for juvenile channel catfish based on weight gain and feed efficiency while potentially increasing disease resistance against E. ictaluri.

The Substitution of Fishmeal with Yeast Culture in the Yellow Catfish (Pelteobagrus fulvidraco) Diet: Growth, Serum Biochemical Indices, and Intestinal and Hepatopancreatic Histology.

Yeast culture is a complex fermentation product consisting of fermentation substrate, yeast cells and their metabolites. This study investigated the potential of yeast culture in replacing fishmeal in the diet of yellow catfish (Pelteobagrus fulvidraco). First, a basal diet was formulated to contain 160 g/kg fishmeal (CON), and then the dietary fishmeal was decreased to 120, 80, 40 and 0 g/kg via yeast culture inclusion, respectively, to form another four isonitrogenous and isolipidic diets (YC-12, YC-8, YC-4 and YC-0). Yellow catfish (3.00 ± 0.10 g) were fed with the above five diets with triplicates per treatment and 40 fish per replicate. After 8 weeks of feeding, the weight gain (WG), protein efficiency rate and protein retention in the YC-12 group and the feed conversion ratio (FCR) in the YC-12 and YC-8 groups showed no significant differences to the CON group (p > 0.05), but the WG in the YC-8, YC-4 and YC-0 groups was significantly lower, and the FCR in the YC-4 and YC-0 groups was significantly higher than in the CON group (p < 0.05). In terms of the whole-body composition, only the crude lipid content in the YC-0 group decreased significantly (p < 0.05). Compared with the CON group, the aspartate aminotransferase and alanine aminotransferase activities and D-lactic acid content in the YC-0 group were significantly increased, and the total cholesterol content was significantly reduced (p < 0.05). The activities of catalase, superoxide dismutase, and alkaline phosphatase, as well as the content of complement C3 and immunoglobulin M, were significantly increased, while the MDA content was significantly reduced in the YC-12 and YC-8 groups (p < 0.05). There were no significant differences in the intestinal amylase and lipase activity among all the groups (p > 0.05), while the trypsin activity in the YC-12 and YC-8 groups, as well as the diamine oxidase in the YC-4 and YC-0 groups, were significantly higher than those in the CON group (p < 0.05). In the intestine histology, there was a significant decrease in the intestinal villus height in the YC-4 and YC-0 groups as well as in the villus width in the YC-0 group (p < 0.05). In the hepatopancreas histology, lipid droplets appeared in the YC-4 and YC-0 groups, and severe cell vacuolation was observed in the YC-0 group. As a summary, in a practical diet containing 160 g/kg fishmeal, yeast culture can effectively replace 40 g/kg fishmeal without negatively affecting the growth performance, nutrient utilization, serum immune and antioxidant, intestinal and hepatopancreas histology of yellow catfish.

Effects of the diet enrichment with β-glucan, sodium salt of butyric acid and vitamins on growth parameters and the profile of the gut microbiome of juvenile African catfish (Clarias gariepinus)

This study assessed the effect of the addition of active substances, i.e., β-glucan, sodium butyrate and vitamins (C, A, D3, E, K) to the diet of juvenile African catfish (Clarias gariepinus) on growth parameters and the intestinal microbiome. For this purpose, a four-week rearing of juveniles African catfish in a recirculating aquaculture system (RAS) under controlled conditions at 25°C was conducted. The fish were fed commercial feed (control group - C), which was enriched with various levels of sodium butyrate and β-glucan (FQV1 – FQV4). After the experiment, growth parameters such as weight gain (WG; g), length gain (LG; cm), specific growth rate (SGR; % d−1), condition factor (K) survival rate (SR; %) and cannibalism factor (CF; %) were determined. The profile of the intestinal microbiome was also determined using Next-Generation Sequencing (NGS) based on the analysis of the 16 S rRNA subunit. The obtained results indicated that feed supplementation with active substances in appropriate doses had a positive effect on the growth parameters of tested fish. Compared to the control group, statistically significant differences were obtained in WG (C - 7.62 g; FQV3 - FQV1 respectively 12.2–16.65 g), in WL (C - 6.23 cm; FQV3 - FQV1 respectively 7.59–8.74 cm), in SGR (C - 4.7%/d; FQV3 – V1 respectively 12.20 – 16.65 g), in K (C – 0.76; V3 – FQV4 respectively 0.80 – 0.84) (P <0.05). In addition, the control group had the highest value of CF (8.0%) compared to the research groups (P <0.05). The values of α-diversity metrics did not show statistically significant differences. However, the number of unique amplicon sequence variants (ASVs) in research groups confirmed that enriching the diet with the active substances increases the biodiversity of intestinal microbiome (C - 203; FQV4 - 373). In research groups and the control group, Firmicutes and Proteobacteria dominated, additionally, an increased number of beneficial lactic acid bacteria (LAB) of the Lactococcus and Bacillus genus was observed, while the number of potentially pathogenic bacteria of the Candidatus genus was reduced (P <0.05). Principal coordinate analysis (PCoA) determining β-diversity showed that the FQV3 was characterized by varied species composition compared to the other groups. The obtained results showed that a carefully selected composition of active ingredients used in the diet of juvenile African catfish has a beneficial effect on the profile and biodiversity of the intestinal microbiome, which indirectly improves resistance to infections and increases breeding indicators.

Effects of dietary Spirulina platensis on growth performance, body composition, haematology, immune response, and gut microflora of stinging catfish Heteropneustes fossilis

The study was conducted to determine the inclusion effect of Spirulina platensis as a feed supplement on growth performance, feed efficiency, body composition, haematology, immune response, and gut microflora of the stinging catfish (Heteropneustes fossilis). Five iso-nitrogenous and iso-lipidic diets were prepared by replacing fish meal (FM) with S. platensis at a rate of 0, 2.5, 5, 7.5, and 10% and referred to as control, SP2.5, SP5, SP7.5, and SP10 diets, respectively. Three replicate groups of fish (average weight of 0.75 g) were reared in glass aquaria (180 L water capacity) and fed with each of the experimental diets up to satiation level twice a day, 7 days a week for 70 days. At termination, growth performance, carcass composition, immune parameters, and gut microflora were assessed. Moreover, ten fish from each aquarium were challenged with Aeromonas hydrophila and cumulative mortality was recorded for 15 days. Significantly (P < 0.05) higher weight gain, specific growth rate (SGR, % day−1), lower feed conversion ratio (FCR), and higher protein efficiency ratio (PER) were recorded in fish fed with SP7.5 and SP10 diets compared to control. Dietary S. platensis inclusion at 7.5–10% levels significantly (P < 0.05) boosted the whole-body protein and ash contents of stinging catfish, while decreasing the lipid and moisture contents compared to the control. Haematological parameters significantly (P < 0.05) improved in the S. platensis supplemented diet compared to the control. Serum lysozyme activity of fish fed with SP7.5 and SP10 diet was significantly (P < 0.05) higher compared to all other diets. Higher inclusion of S. platensis lowered post-challenge mortality and the lowest cumulative mortality (30%) was recorded in fish fed with the SP7.5 diet compared to the control (70%). Pseudomonas, Lactobacillus, and Lentibacillus were the prevalent genera in the gut microbiota found in the metagenomics study and the abundances of the above microbiota gradually increased with the level of dietary S. platensis inclusion. Based on the findings of the study, 7.5–10% inclusion of S. platensis was the most recommendable in stinging catfish diet to improve growth performance, feed utilization, body composition, haematology, immunological response, and gut microbiology. However, based on the regression analysis the optimum inclusion level of S. platensis as a feed supplement was calculated to be 9.3–9.9% in stinging catfish.

Microalgae as fishmeal alternatives in aquaculture: current status, existing problems, and possible solutions.

Fishmeal is an indispensable ingredient for most aquatic animals. However, the finite supply and escalating price of fishmeal seriously limit its use in aquaculture. Thus the development of new, sustainable protein ingredients has been a research focus. Microalgae are potential fishmeal alternatives owing to their high protein content and balanced amino acid profile. Studies suggest that suitable replacement of fishmeal with microalgae is beneficial for fish growth performance, but excessive replacement would induce poor growth and feed utilization. Therefore, this paper aims to review research on the maximum substitutional level of fishmeal by microalgae and propose the main issues and possible solutions for fishmeal replacement by microalgae. The maximum replacement level is affected by microalgal species, fish feeding habits, quality of fishmeal and microalgal meals, and supplemental levels of fishmeal in the control group. Microalgae could generally replace 100%, 95%, 95%, 64.1%, 25.6%, and 18.6% fishmeal protein in diets of carp, shrimp, catfish, tilapia, marine fish, and salmon and trout, respectively. The main issues with fishmeal replacement using microalgae include low production and high production cost, poor digestibility, and anti-nutritional factors. Possible solutions to these problems are recommended in this paper. Overall, microalgae are promising fishmeal alternatives in aquaculture.

Effects of Vitamin A Supplementation in Female Broodstock Diets of African Catfish on Egg Quality, Egg and Liver Retinol, Ovary Estradiol, and Larval Survival

Effects of Vitamin A Supplementation in Female Broodstock Diets of African Catfish on Egg Quality, Egg and Liver Retinol, Ovary Estradiol, and Larval Survival

Glycerol derived from biodiesel can replace maize in diets for juvenile silver catfish (Rhamdia quelen).

The aim of the present study was to evaluate the effect of maize replacement by crude biodiesel-derived glycerol on the zootechnical performance, chemical carcass composition and blood parameters of silver catfish (Rhamdia quelen) juveniles. A total of 600 silver catfish juveniles were distributed in a completely randomized design with six treatments comprised of isoproteic and isoenergetic pelleted diets with six levels of glycerol replacing maize, and five replicates. The glycerol maize substitution significantly influenced (p < 0.05) the final weight, clean trunk production and headless carcass yield, with the highest values for both parameters observed in the 100% substitution treatment, significantly different compared to the 0% replacement treatment. Plasmatic calcium, alkaline phosphatase, glucose, total proteins, oxaloacetic and pyruvic glutamic transaminase concentrations were not influenced (p < 0.05) by the dietary treatments, nor were moisture, crude protein and mineral matter (p < 0.05). Crude glycerol can be included in up to 7.5% in juvenile silver catfish diets. Biodiesel-derived glycerol can, thus, successfully replace maize in juvenile silver catfish diets.

Corrigendum to: Unravelling a specialised diet of an Amazonian catfish in a controlled flood-pulse area by combining stomach-content and stable-isotope analyses

Corrigendum to: Unravelling a specialised diet of an Amazonian catfish in a controlled flood-pulse area by combining stomach-content and stable-isotope analyses