The aim of this study was to examine the impact of the probiotics Saccharomyces cerevisiae (SC) and Pediococcus acidilactici (PA), as well as the prebiotic yeast cell wall extract (Cyberlindnera jadinii and S. cerevisiae) (YP), on the growth parameters, intestinal histomorphology, liver and gills normality, and gut microbiome of common carp (Cyprinus carpio L.). These feed supplements were subjected to a 60-day experimental period, during which 120 fish (26.4 ± 5.2 g) were distributed into four groups, with each group comprising 30 fish. The feed supplements were administered at a rate of 1 g/kg of body weight. Before the trial, the fish were acclimatized for two weeks, then injected with Passive Integrated Transponder (PIT) tags. The results showed that none of the feed supplements exhibited a significant effect (p > 0.05) on growth indices. In contrast, the villi length, villi width, muscular thickness, and crypt depth in the anterior, mid, and posterior intestine of the SC group exhibited significant (p < 0.05) improvements compared to the other groups. No alteration or abnormal growth were noticed in the gills and livers. The most dominant microbe genera in all groups, with abundances greater than 60% of the total, were Cetobacterium and Aeromonas. However, Polynucleobacter, Nordella, Mycoplasma, Romboutsia, and Staphylococcus species were present at lower abundances. The presence of Actinobacteria has been observed only in the intestine of fish that have been fed a diet supplemented with PA. It can be concluded that the tested probiotics and the yeast cell wall prebiotic have the potential to produce a remarkable improvement in intestinal morphology and a considerable change in the gut microbiome without notable effect on growth, livers, or gills of common carp.

This review examines the significance of live feeds in commercial aquaculture industry for production of fish and shrimp larvae, along with various challenges and prospects. Live feeds are an essential food source in larviculture, especially for marine fish, which depend on them for nutrition during the initial days of exogenous feeding. They are palatable, highly digestible, and their movement stimulates natural hunting and foraging instincts, promoting better development, lowering captivity stress, and increasing survival rates. Artemia is the most commonly used live feed in larviculture; however, it has low levels of omega-3 HUFA. Copepods are the most nutritionally rich live feed, containing high levels of DHA and EPA. Despite these benefits, they are less frequently used in larviculture due to technical challenges associated with large-scale cultivation at high densities. The use of live feed is labour-intensive and costly. The feeding period for fish larvae can be shortened using a co-feeding strategy. Microalgae rich in DHA have been utilized to enrich live feeds. Further research is needed to determine the most effective approach to significantly reduce the weaning time of fish larvae from live feed. This will lead to gradual and eventual complete replacement of life feed in the near future.

This study aimed to evaluate growth performance, amino acid and fatty acid composition of fillets, and blood biochemistry of hybrid catfish ( Heteroclarias ) cultured on Black Soldier Fly (BSF), Hermetia illucens larval‐based diets. The experiment was conducted in a recirculating system, circular poly tanks (350 L), in a completely randomized design. Four isonitrogenous (400 g kg ⁻¹ crude protein) and isolipidic (140 g kg ⁻¹ crude fat) diets were formulated in which fishmeal (400 g kg ⁻¹ ) was replaced at 0%, 25%, 50%, and 75% with defatted BSF larval meal and fish oil was completely replaced with corn oil in the test diets. 180 hybrid African catfish (12 weeks post‐hatching) with an initial body weight of 200 ± 25 g were randomly distributed in the 12 experimental tanks (15 fish per tank, 45 fish per treatment) and were hand‐fed at 3% body weight for 8 weeks. The findings showed that replacing 50% of fishmeal with BSF meal resulted in the highest growth performance (final weight, weight gain, specific growth rate [SGR], thermal growth coefficient [TGC]). However, at 75% level, growth performance and nutrient utilization (FCR, PER) significantly decline ( p < 0.05). The dietary modification had no significant impact ( p > 0.05) on organosomatic indices, proximate composition, amino acid profile, deposition, or retention of arachidonic acid (ARA), eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and sum n‐3 polyunsaturated fatty acids (PUFA) in fish fillets. There were no significant differences in the hematological parameters ( p > 0.05) across all treatments. Except for a reduction in globulin and cholesterol levels, all the plasma metabolites, including alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels, remained stable ( p > 0.05). Overall, the findings of this study suggest that BSF larval meal may partially replace dietary fishmeal up to 50% (200 g kg ⁻¹ ), and corn oil may completely replace fish oil in a practical diet for hybrid African catfish without exerting adverse impacts on growth, feed conversion efficiency, fillet quality, health status, and physiological well‐being.