The roles of polysaccharides in tilapia farming:A review

Impairment of fish growth and immune system due to stress and disease are major constraints in aquaculture industry.Traditionally,antibiotic was used as prophylactic agent in the health management of aquaculture species.However,antibiotic only provide a temporary solution to the problem of disease outbreak.Over-reliance on antibiotic also has led to the increasing cases of antibiotic resistance among pathogenic bacteria from aquaculture sites and contamination of antibiotic residues into human food chain.Probiotic,prebiotic and symbiotic are therefore suggested as alternatives to prophylactic antibiotic to be used in the aquaculture industry.A potential prophylactic agent is polysaccharide that could be developed into an alternative antibiotic for aquatic animals.In this review paper,definition,sources,and mode of action of polysaccharide are presented.The roles of polysaccharides in fish farming with emphasis on growth improvement,immune system enhancement,disease resistance stimulation in tilapia farming,and the effects of polysaccharides on abiotic stressors are summarized and discussed.

Editorial special issue:Friendly nutritional strategies for sustainable aquaculture

The aquaculture sector provides the primary protein source for the global population while generating income and revenue(FAO,2020).Apart from that,aquaculturists are responsible for developing and maintaining sustainable production methods,including aquafeed production(Albrektsen et al.,2022).

Multi-species probiotics enhance survival,growth,intestinal microbiota and disease resistance of rohu(Labeo rohita)larvae

Multi-strain probiotics provide the most dependable approaches to improve health,immune response,and disease resistance in farmed fishes.In the present study,we examined the effects of multi-species probiotics on the survival,growth,immune response,and disease resistance of rohu(Labeo rohita)larvae.Newly hatched larvae from the day of first feeding(average weight of 0.003 g)were reared with multi-species probiotics having a combination of Bacillus subtilis(109 colony forming units(cfu)/mL)and Lactobacillus spp.(Lactobacillus plantarum,Lactobacillus buchneri-1011 cfu/mL)in water containing doses of 0(control-C),0.5 mL/L(treatment 1-T1),and 1.0 mL/L(treatment 2-T2)in triplicates for 90 days.After the experiment,a challenge test was performed to assess the fish's resistance to pathogenic Aeromonas veronii.Significantly higher survival was recorded in larvae of treated groups(87%in T2 and 79%in T1)compared to the control(62%).Significantly higher growth performance(weight gain and specific growth rate—SGR)was shown by the probiotic-treated larval groups compared to the control.Probiotic supplementation resulted in significantly higher counts of total viable colony(TVC)and lactic acid bacteria(LAB)in the intestine.Some immunological parameters(mucosal fold fattening,goblet cell abundance,expansion of lamina propria and enterocytes)of the gut were significantly better in probiotic-treated fish.The liver of treated fish showed irregular shape nuclei turning into regular shape and reducing spaces between the hepatic cells.Probiotic-treated fish had the highest post-challenge survival rate(90%)against A.veronii infection.The erythrocytes of challenged fish treated with probiotics had significantly lower frequencies of various nuclear and cellular abnormalities.These findings suggest that multi-species probiotic supplements could improve the survival,growth,health status,and immune response of rohu in the early stages of its development.

Recent advances in the utilization of insects as an ingredient in aquafeeds:A review

The aquafeed industry continues to expand in response to the rapidly growing aquaculture sector.However,the identification of alternative protein sources in aquatic animal diets to replace conventional sources due to cost and sustainability issues remains a major challenge.Recently,insects have shown tremendous results as potential replacers of fishmeal in aquafeed.The present study aimed to review the utilization of insects in aquafeeds and their effects on aquatic animals’growth and feed utilization,immune response and disease resistance,and fish flesh quality and safety.While many insect species have been investigated in aquaculture,the black soldier fly(Hermetia illucens),and the mealworm(Tenebrio molitor)are the most studied and most promising insects to replace fishmeal in aquafeed.Generally,insect rearing conditions and biomass processing methods may affect the product’s nutritional composition,digestibility,shelf life and required insect inclusion level by aquatic animals.Also,insect-recommended inclusion levels for aquatic animals vary depending on the insect species used,biomass processing method,and test organism.Overall,while an appropriate inclusion level of insects in aquafeed provides several nutritional and health benefits to aquatic animals,more studies are needed to establish optimum requirements levels for different aquaculture species at different stages of development and under different culture systems.