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Gut microbiota in fish plays an important role in the nutrient digestion, immune responses and disease resistance. To understand the effect of fluoroquinolone antibiotic bath administration on fish gut microbiota, the gut microbiota community in the coral trout Plectropomus leopardus (Lacepède, 1802) was studied after enrofloxacin bathing treatment at two concentrations (5 and 10 mg/L) and 0 mg/L as control. A total of 90 fish were used in this study, and three replicates were used for each treatment. After a 24‐hr bath, the gut bacterial composition was analyzed using high‐throughput Illumina sequencing. The results indicated that the richness, diversity and the dominant bacterial taxa of P. leopardus gut bacteria were not affected by enrofloxacin bathing (p > .05). Proteobacteria and Firmicutes were the dominant phyla, and Exiguobacterium, Citrobacter, Vibrio, Acinetobacter, Pseudomonas were the dominant genus. The findings in the present study provide an understanding on the relationship between fish gut bacteria community and antibiotic bath administration. The findings of this study are instructive on the antibiotic bath administration applied for the management of P. leopardus health in aquaculture., The gut microbiota community in the coral trout Plectropomus leopardus (Lacepède, 1802) was studied after enrofloxacin bathing treatment at two concentrations (5 and 10 mg/L) and 0 mg/L as control. After a 24‐hr bath, the gut bacterial composition was analyzed using high‐throughput Illumina sequencing. The results indicated that the richness, diversity and the dominant bacterial taxa of P. leopardus gut bacteria were not affected by enrofloxacin bathing (p > .05).

To understand the impacts of peanut worms Sipunculus nudus on the prokaryotic community composition in a tidal flat, an onsite investigation was conducted in Suixi in the Beibu Gulf (109.82E, 21.35N) in the burrow sediments, non‐burrow sediments and the sediments without peanut worm disturbance (control). The16S rRNA gene Illumina MiSeq sequencing was used to investigate the microbial communities and their response to bioturbation by S. nudus in a sandy tidal flat. A total of 18 bacteria phyla were detected, and Proteobacteria and Cyanobacteria constituted the majority of the prokaryotic community in the samples. The distribution of the relative abundances of genera showed that approximately 6.99%–17% of the reads in the samples were classified into 25 known genera. Sulfate‐reducing bacteria (Desulfococcus and Desulfosarcina) were the most abundant taxa, followed by Thermodesulfovibrionaceae LCP‐6, indicating that sulfate reduction is the main process in the sandy tidal flat. The abundances of Desulfococcus, LCP‐6 and Cyanobacterium in the non‐burrow sediment were greater than in the burrow sediment, suggesting that the anoxic condition is more suitable for Desulfococcus and LCP‐6 when the activity of S. nudus is absent. The biomass of Cyanobacterium was decreased by the feeding bioturbation of S. nudus. Meanwhile, the relative abundance of the Bacteroidetes Luteimonas in the burrow sediments was significantly greater than in the non‐burrow sediment, and there was a strong relationship between S. nudus bioturbation and increased in oxygen contents and oxidation‐reduction potentials in the burrow sediment. The abundances of Desulfococcus and LCP‐6 were greater in the middle layer (20–30 cm) than in the top layer in the non‐burrow sediment. However, the middle and bottom layers (20–30, 30–40 cm) had higher abundances of these genera than did the upper layers (0–10, 10–20 cm) in the burrow sediments. The abundances of the Fusobacteria Propionigenium and the Spirochaetes Spirochaeta were greater in the middle and bottom layers (20–30 cm, 30–40 cm) than in the top layers (0–10, 10–20 cm) in the burrow sediment, but this phenomenon was not found in the non‐burrow sediment. This study demonstrates that bioturbation by S. nudus plays an important role in reshaping the bacterial community composition in intertidal regions.

The Pacific white shrimp Litopenaeus vannamei is a euryhaline species with optimal salinity of 20–25 practical salinity unit (psu) for growth and survival, but has been cultured in inland water with salinity

Temperate abalone species in aquaculture have a grow-out period of approximately 3 years because of their slow and heterogeneous growth rate. Abalone aquaculture is still a developing industry, and at least two major issues, nutrition and health, impede its development. Abalone are fed macroalgae on-farm in a number of countries, including China, Korea, South Africa and Chile. Formulated diets are crucial to the success of abalone aquaculture in countries where abalone do not grow readily when fed brown macroalgae or when access to macroalgae is insufficient for culture. Typically, the growth rate of abalone fed formulated diets is higher than abalone fed live macroalgae. However, due to a long production period, diets for abalone not only need to sustain high growth rates, but also maintain optimal health. Feeding live macroalgae improves the feeding activity, health and marketability of abalone. In this review, the nutritional requirements of abalone and dietary ingredients used in formulated diets will be discussed, together with the use of dried macroalgal meal as a dietary ingredient in formulated diets to improve the feeding activity, health and marketability of abalone in commercial production.

Temperature is one of the most important physical factors influencing fish growth. Under optimal temperatures, food energy partitioned into fish growth can be maximized. However, when a marine carnivorous species is cultured in an environment where temperature falls outside the optimal range of a fish, growth will be affected. The nutrient–environment interaction is important for optimizing a fish’s nutritional requirements throughout the grow-out period. The most current global issue for the aquaculture industry is the inclusion of alternative ingredients into formulated diets to produce a sustainable seafood product. This requires the substitution of fish meal and fish oil with alternative ingredients from plant and terrestrial animal sources. This review discusses the changes in nutritional requirements (protein, lipid and energy) and physiology of some commonly cultured marine fishes as a consequence of seasonal changes in temperature during the grow-out period. This review also discusses the effects of replacing fish meal and fish oil with alternative protein and lipid sources on the nutritional–environmental interactions of fish performance at different temperatures.

The dietary requirement of vitamin B6 (pyridoxine) of Pacific white shrimp, Litopenaeus vannamei, at 3‰ salinity was evaluated by examining the growth responses, survival, and amino transferase activities. The basal diet was formulated using vitamin-free casein as the protein source. Six levels (0, 35, 70, 105, 140, and 200 mg/kg diet) of vitamin B6 were added to the basal diet, yielding the final vitamin B6 contents of 2.17, 32.43, 65.79, 96.97, 137.13, and 189.56 mg/kg, respectively. Each diet was fed to the triplicate groups of shrimp for 30 d. Percent body weight gain and condition factor of shrimp significantly increased with the increasing levels of dietary vitamin B6 up to 137.13 mg/kg diet. Exceeding this level, however, did not further improve the weight gain. The survival rate also increased at each incremental increase of dietary vitamin B6, but no significant increase was observed beyond 65.69 mg/kg. Both glutamic oxalacetic transferase (GOT) and glutamic pyruvic transferase (GPT) activities increased with increasing levels of dietary vitamin B6 and the maximum value reached at 96.97 mg vitamin B6/kg. No significant differences were observed in both GOT and GPT activities of the shrimp-fed diets containing 96.97, 137.13, and 189.56 mg vitamin B6/kg. Broken-line regression analysis using weight gain, specific growth rate, and amino transferase activities indicates that the optimal dietary vitamin B6 requirement is 106.95‐151.92 mg/kg at 3‰ salinity.