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Two trials were conducted with different durations and intensities of food deprivation to investigate the compensatory growth, food utilization and body composition of the ricefield eel, Monopterus albus. The different feeding protocols were tested for 64 days in two stages: experiment 1 comprised four levels of feed deprivation (1‐day starvation and one‐day refeeding (S1F1), 2‐day starvation and 2‐day‐ refeeding (S2F2), 4‐day starvation and 4‐day refeeding (S4F4), 8‐day starvation and 8‐day refeeding (S8F8)) and a control level (daily feeding). Experiment 2 comprised three levels of deprivation (1‐day starvation and 2‐day refeeding [S1F2], 1‐day starvation and 3‐day refeeding [S1F3], and 1‐day starvation and 4‐day refeeding [S1F4]). In experiment 1, the final body weight and specific growth rate (SGR) of the fish in all feed deprivation groups were significantly lower than those of the control; however, the feeding rate (FR) in all feed deprivation groups was significantly higher than that of the control. The feed efficiency (FE) in the feed deprivation groups was significantly lower than those of the control. In experiment 2, the final body weight and SGR in S1F3 and S1F4 approached the mean weight of the control. FR increased in S1F3 and S1F4, but FE did not differ among groups and was higher than in experiment 1, indicating that feed utilization efficiency increased with prolonged refeeding time. Overall, under the experimental conditions, feed restriction for 1 day followed by longer refeeding might represent an adequate management strategy in M. albus rearing.

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A 120‐day feeding trial was conducted to assess the effect of dietary protein levels on growth performance, serum indexes, PI3 K/AKT/mTOR/S6 K signalling pathway and intestinal microbiota of abalone Haliotis discus hannai. Abalones (initial body weight: 15.88–16.54 g; initial shell length 41.70–42.40 mm) were fed nine isoenergetic (~16.08 kJ/g) and isolipidic (~42.0 g/kg) experimental diets with 93.5, 116.9, 151.1, 191.8, 230.3, 275.9, 320.3, 360.5 and 405.9 g/kg protein contents, respectively. Results showed that the optimal dietary protein level for H. discus hannai was determined as 259.4 g/kg through second‐order polynomial regression analysis for weight gain rate (WGR). Serum TP and urea nitrogen levels were significantly increased when dietary protein levels were higher than 320.3 g/kg (p < .05). The highest gene expressions of phosphatidylinositol 3 kinase (PI3 K), target of rapamycin (mTOR) and ribosomal protein S6 kinase (S6 K) in muscle were found in the treatment with 275.9 g/kg of dietary protein. The excessive dietary protein level (405.9 g/kg) significantly decreased the gene expression of S6 K. Meanwhile, abalone fed with 275.9 g/kg of dietary protein exhibited the highest microbial diversity in intestine as measured by Chao richness and Shannon diversity index. In conclusion, dietary protein level reduced from 259.4 g/kg to 154.0 g/kg or increased from 259.4 to 323.0 g/kg, the WGR of abalone might be depressed with 5% likelihood. Over high (>360.5 g/kg) or low (<151.1 g/kg) dietary protein levels had negative effects on growth performance, serum indexes, PI3 K/AKT/mTOR/S6 K signalling and microbial diversity in intestine of abalone.