Summary This study reports the length–weight relationships (LWRs) of four small indigenous species, Trichogaster lalius (Hamilton, 1822), Nandus meni (Hossain & Sarker, 2013), Lepidocephalichthys annandalei (Chaudhuri, 1912) and Botia dario (Hamilton, 1822) collected between July 2015 and August 2016 from fishermen's catches landed in an inland fish landing center, northeastern Bangladesh. In the study, a new maximum total length (TL) is given for L. annandalei and LWRs of three species T. lalius, N. meni and L. annandalei for the first time in FishBase. Estimated LWRs were W = .014 TL3.17, (r2 = .982) for T. lalius, W = .006 TL3.38, (r2 = .961) for N. meni, W = .004 TL3.27, (r2 = .965) for L. annandalei and W = .020 TL2.87, (r2 = .978) for B. dario.

Solvent-extracted soybean meal (SBM) was fermented using baker's yeast Saccharomyces cerevisae at 30 °C for 5 days. Four isonitrogenous and isocaloric diets containing 75% SBM protein, either fermented or non-fermented (SBM and FSBM), and supplemented or not with organic Se (OS) (SBM and FSBM), were fed to triplicate groups of juvenile barramundi (Lates calcarifer) (initial weight of 5 g) for 75 days. A fishmeal (FM)-based diet formulated for juvenile barramundi was used as a reference diet. The growth of fish was significantly affected by either the interaction of SBM type or by the OS level. In fish fed diets supplemented with OS (SBM and FSBM), final weight (FW), specific growth rate (SGR) and weight gain (WG) were higher in fish fed the fermented SBM (FSBM) than in those fed the non-fermented SBM (SBM). The apparent digestibility coefficient (ADC) of protein was higher in the fish fed the fermented SBM, either supplemented or unsupplemented with OS. However, there were no significant differences in the ADC of dry matter (DM) and lipids among the tested diets and in comparison to the reference diet. The haematocrit and leucocrit of fish fed the FSBM diet were lower than those of fish fed the FM diet. Furthermore, glutathione peroxidase (GPx) activity was significantly influenced by OS supplementation in the experimental diets; GPx activity was greater in the fish fed diets supplemented with OS. Creatinine kinase (CK) of all groups of fish was higher than the CK of those fed the reference diet. These results suggest that with a proper nutritional level, OS supplementation may act as an important factor in enzymatic GPx activity and in the haematology and blood biochemistry status of juvenile barramundi fed fermented SBM-based diets, encouraging improvement of the overall growth performance.

The aim of this study was to investigate the interactive effects of temperature and dietary selenium concentrations on antioxidant capacity, muscle histochemistry and the growth, of juvenile yellowtail kingfish (Seriola lalandi). The yellowtail kingfish were exposed to two temperatures (21C or 26C) and three selenium levels (0.0, 2.0 or 4.0 mg Se kg −1 of feed) for 30 days. Final weight and specific growth rate (SGR) were significantly affected by water temperature (ρ<0.001) and dietary Se (ρ<0.001) supplementation, and there were significant differences in the interaction between these two factors. Juvenile yellowtail kingfish fed Sesupplemented diets, attained a higher final weight and SGR than those without Se supplementation at 21C, but not at 26C. Regardless of the temperature, the red blood cell (RBC) glutathione peroxidase (GPx) activity of yellowtail kingfish fed Se-supplemented diets was significantly higher (ρ<0.05) than with the control diet. However, GPx activity of yellowtail kingfish when fed either 2.0 mg Se kg −1 or 4.0 mg Se kg −1 showed no significant difference (ρ>0.05). Se concentration in the muscles of juvenile yellowtail kingfish fed Se-supplemented diets was higher than that of the yellowtail kingfish that were fed the control diet. A histopathological test confirmed that 20.3% of fish muscles exhibited lesions, which occurred in the absence of dietary Se. The outcome of the present study helps in understanding the interactive effects of dietary Se concentrations and the temperature in the farming of yellowtail kingfish.