The background colour of the fibreglass tanks attributed to their significant correlation with light intensity and spectrum serves as one of the major factors influencing growth performance and stress levels of cultured fish. Moreover, it plays a key role in the successful production of the cultured species, which is challenging under confinement conditions. On the other hand, Asian sea bass (Lates calcarifer) has received significant attention among researchers due to its high‐profit value and growing demand in the global market. Hence, the current study was designed to investigate the effects of different tank background colours (white, red, black and blue) on growth indices, body composition, digestive enzymes, haematological parameters, expression of stress and growth‐related factors in L. calcarifer. Therefore, fish (160.90 ± 6.0 g) were distributed into 12 fibreglass tanks (250‐L) including four treatments in triplicates and were reared for 6 weeks. According to the present results, the highest specific growth rate was observed in fish raised in red‐coloured tank followed by white and black tanks. Maximum weight gain (WG) and high protein efficiency ratio (PER) were observed in fish raised in red‐coloured tank followed by white‐, black‐ and blue‐coloured tanks, respectively. Modulation of the main digestive enzymes was observed across four treatments indicating different strategies for the utilization of nutrients by fish. Fish from red‐ and white‐coloured tanks showed a lower level of cortisol and higher levels of heat shock protein (HSP70) when compared to the other groups. The present findings indicate that red colour is the most suitable background colour for rearing Asian sea bass juveniles followed by white colour compared with the other ones.

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In the present study, Asian seabass (Lates calcarifer) with an initial mean body weight of 29.0 ± 1.0 g (in your materials and methods -31.0 g- which one is correct?) has been used as a model organism to establish the effects of dietary of Sargassum ilicifulium and Padina australis, as partial substitution of fish meal on growth performance, body composition, hemato-immunlogical response, digestive enzymes and immune and growth-related genes. Three diets were formulated in which fish meal (FM) was gradually replaced by S. ilicifolium (SIM) and P. australis meal (PAM) at 6% (S6 & P6, respectively) whereas in the control diet (C), FM was not replaced with macroalgae. Asian seabass juveniles were fed for six weeks with experimental diets. At the end of the experiment, growth and feed utilization parameters in P6 group were significantly higher than those of the control group (P < 0.05). The P. australis dietary supplementation showed differences significantly in RBC, Hb, Hct, WBC to write in full during 1st mention, lymphocytes, neutrophils, and cholesterol contents (P < 0.05). It was observed that the levels of total protein and triglyceride in fish fed S. ilicifulium diet significantly increased compared to the other groups (P < 0.05). The skin mucus total immunoglobulin (Ig) and mucus lysozyme in the group fed on P6 were significantly higher than the control group (P < 0.05). The serum total Ig in the group fed on S6 was significantly higher with respect to the control group (P < 0.05). No significant differences were recorded in the contents of ACH50 in full during 1st. mention and serum lysozyme among all treatment groups (P > 0.05). There was no significant difference in the contents of protease, lipase, and amylase among all treatments (P > 0.05). At the end of the experiment, the insulin-like growth factor I (IGF-I), lysozyme (LZ), and interleukin-1β (IL-1β) in P6 were significantly higher than other treatments (P < 0.05). The results obtained in the present study showed that P. australis as a partial replacement for fishmeal in the diet of Asian sea bass juveniles is beneficial for its immune system and growth performance stimulatory effects.

The effects of using a commercial probiotic mixture (PM) (Bacillus licheniformis, Bacillus sabtilis, Pedicoccus acidilactici and Lactobacillus acidophilus with a total count of 107 CFU/g) on water quality, bacterial population and the survival of Acanthopagrus latus larvae were evaluated during a 24-hour simulated transportation experiment. The one-day-old larvae were transported using purified seawater (as control) and purified seawater supplemented with 3 g of PM (as PM48 treatment). For the PM48, 3 g of PM was added to 1 L of purified seawater and after 30 min, mixed with 200L of purified seawater 48h prior to the main experiment. The obtained results showed that the use of probiotics led to an increase in larval survival up to 93.3%. Statistically, difference was found between control and PM48 at the initial sampling in terms of NO2. The pH of the control treatment showed a significant decrease at the end of the experiment. The investigation of a total number of bacteria and the total number of Vibrio spp. in water and fish larvae showed that within 48 hours, the probiotics became the dominated population in PM48 treatment. After 24 hours, water samples and larvae of control treatment showed a significant increase in bacterial load. In general, the obtained results showed that the use of probiotics played a significant role in maintaining water quality chemically and bacterially and caused more survival of larvae during transportation.