The effects of tuna viscera hydrolysate (TVH) on juvenile pompano Trachinotus blochii, growth performance, nutritional response, intestinal and liver health, and resistance to Streptococcus iniae were investigated in this study. Five isonitrogenous and isocaloric diets (protein 46.0%, lipid 10.0%) were formulated in which TVH was added to replace fishmeal protein at levels of 0 (control), 30, 60, 90, and 120 g kg-1, labelled as TVH0, TVH05, TVH10, TVH15, and TVH20, respectively. Triplicate groups of pompano were fed the respective diets for ten weeks. The results showed that fish fed diets containing TVH10 produced significantly higher final body weight and specific growth rate in comparison to the fishmeal control ( P < 0.05 ). Dietary TVH did not produce any effect on feed utilisation, somatic indices, and proximate composition of juvenile pompano ( P > 0.05 ). While most amino acids were unchanged by the dietary inclusion of TVH, phenylalanine and valine levels were significantly lower in the fish fed TVH20 diet compared to the control. Fish fed the TVH20 diet had significantly lowered total serum protein compared to the TVH10 treatment, whereas other biochemical parameters in the blood did not show any difference among treatments. The intestinal histology indicated a significant increase in goblet cell numbers in fish fed TVH10 diet. Fish fed diet supplemented with TVH showed the highest disease resistance against Streptococcus iniae after 14 days of challenge. Based on a quadratic regression between final body weight and dietary TVH levels, the optimum TVH was calculated to be 10% or 60.0 g kg-1 for maximum growth performance when fed to pompano.

Summary The present ichthyological report describes the length‐weight relationships (LWRs) of three catfish species (Eutropiichthys murius, Nangra nangra and Gagata viridescens) belonging to two families from the Kaliganga River, a tributary of the Dhaleshwari River, Bangladesh. The analyses included 306 specimens collected monthly from fishermen's catches during October 2015 to April 2016. Ranges of regression parameters a and b of the three species were within 0.0058–0.0099 and 2.900–3.142, respectively with highly correlated coefficients of determination (r2 > .995; p < .001). The LWRs for all three species presented herein for the first time with a new maximum length record for N. nangra.

The present study examined the efficacy of dietary selenium-enriched spirulina (SeE-SP) on growth performance, antioxidant response, liver and intestinal health, immunity and disease resistance of Asian seabass, Lates calcarifer. A total of 480 seabass juveniles with an initial weight of 9.22 ± 0.09 g/fish were randomly assigned to four dietary groups. The fish were fed a fishmeal protein replacement diets with SeE-SP at 5%, 10%, and 20%, namely SeE-SP5, SeE-SP10, and SeE-SP20, and a fishmeal-based diet as control for 8 weeks. The results indicated that seabass juveniles fed SeE-SP5 and SeE-SP10 diets grew at the same rate as the fish fed a fishmeal-based control diet after 8 weeks of feeding, while SeE-SP20 grew at a significantly lower rate than the control (p < 0.05). Although most of the measured biochemical parameters were not influenced by the Se-SP diets, serum antioxidant-enzyme glutathione peroxidase (GPx) and immunological indices, such as lysozyme activity and immunoglobulin-M, were found significantly higher in the SeE-SP5 and SeE-SP10 diets compared to control. In addition, the fish fed the SeE-SP5 diet showed significantly lower mortalities after the 14-day of bacterial challenge with V. harveyi. These outcomes indicated that up to 10% inclusion of SeE-SP in the diet of juvenile Asian seabass does not compromise growth, while SeE-SP5 enhanced disease resistance in juvenile seabass.

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A 60-day feeding trial was carried out to investigate the effects of fish protein hydrolysate (FPH) in high lupin meal (LM) diets on growth, health and immunity of barramundi. Fish were fed a fishmeal-based control diet (FM) and three test diets to replace 75% fishmeal protein in the control diet by lupin meal alone (LM), lupin meal with FPH (LM+FPH) and fermented lupin meal with FPH supplementation (FLM+FPH). Each dietary group was stocked with 120 fish with an initial weight of 6.18 ± 0.08 g and fed three times daily to apparent satiation. Fish fed the LM diet had significantly lowered final body weight and specific growth rate compared with control and the remaining dietary groups (p < .05). The decreased growth performance was further exacerbated by liver steatosis and necrosis in the kidney of LM-fed fish. Fish fed the FLM+FPH diet had significantly increased white blood cells and protein contents compared with the control. A significant reduction in mortality was observed in fish fed FLM+FPH compared with fish fed the LM diet following a 14-day challenge with Vibrio harvei.Overall, this study suggests that high LM diets with FPH supplementation could be incorporated into the diet of juvenile barramundi without compromising growth and health.

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An 8‐week feeding study was carried out to assess the effects of dietary protein and lipid levels on growth, feed utilization and body composition of juvenile giant trevally (Caranx ignobilis Forsskal, 1775). Six diets were produced with three crude protein levels of 42%, 47%, 52% and two crude lipid levels of 10% and 18% in a 3 × 2 factorial design. Treatments were named by their protein and lipid levels, viz. P42:L10, P42:L18, P47:L10, P47:L18, P52:L10 and P52:L18, corresponding P/E of 20.23, 18.73, 22.31, 20.81, 24.63 and 22.12 g/MJ respectively. Growth performance in terms of length, final body weight and specific growth rate were the highest (p < 0.05) when juveniles were fed P52:L10 with P/E of 24.63 g/MJ. The same diet also resulted in the highest effective feed utilization in terms of feed intake and feed conversion ratio. Crude protein in whole body increased when dietary protein or dietary lipid increased from 42% to 52% and 10% to 18% respectively. Significantly increased levels of amino acids in fish's body, including alanine, aspartic acid, glutamine, serine, leucine, threonine, valanine and arginine, were observed in fish fed 52% protein. Increasing dietary lipid from 10% to 18% led to reduced levels of alanine, glutamine, leucine, threonine, valine and arginine in fish. The result suggests that P52:L10 diet with P/E ratio of 24.63 g/MJ subjects the growth requirement of juvenile giant trevally.