A 50-day feeding trial was conducted for juvenile pearl gentian grouper (Epinephelus lanceolatus ♂ 9 Epinephelus fuscoguttatus ♀) to determine the optimal amount of Tenebrio molitor meal (TM) that could replace fishmeal (FM) in feeds without reducing growth performance, antioxidant enzyme activities and resistance. Six isonitrogenous and isolipidic diets were formulated with TM replacing 0% FM respectively. Each diet was randomly divided into triplicate groups with 30 juveniles (initial weight 6.60 AE 0.00 g). After feeding trail, fish were challenged by Vibrio harveyi for 7 days.The results showed that each treatment had better survival rate between 96.67% and 100%. Fish fed with control and T6 diet showed lower final weight and weight gain rate as compared to other diets. The feed conversion ratio of fish fed on T12 and T18 diet had no significant difference compared to control diet. As compared to control diet, other diets had no significant differences on specific growth rate and temperature growth coefficient. Fish fed with T6 diet had highest liver glutathione reductase activities. No significant differences were observed in liver superoxide dismutase activities in fish fed with T6, T12, T25, T31 and control diet.Fish fed on T18 diet had lowest hepatic malondialdehyde contents and a highest relative per cent survival. According to a broken-line model, the recommended substituted ratio of TM for FM was estimated to be 12.3% for grouper obtaining maximum WGR, corresponding to additive amount of TM is 4.92%.

Wnt/β-catenin signalling plays an essential role in the immunity of Penaeus vannamei. In this study, the effects of dietary Wnt/β-catenin pathway activator TWS119 on the growth, immunity, and transcriptome response in P. vannamei were investigated. Penaeus vannamei were fed diets with added TWS119 at doses of 0 (T0), 0.25 (T0.25), 1 (T1), 4 (T4), 16 (T16), or 64 mg·kg−1 (T64), respectively. LvGSK3β activity was effectively inhibited in P. vannamei given TWS119. The growth of P. vannamei in the T16 group was significantly improved when compared with the control group. After Vibrio parahaemolyticus infection, the survival rates (SRs) of P. vannamei in all experimental groups except the T64 group were significantly higher than in the T0 group. Compared with the control group, the immune enzymes’ activities in the serum of P. vannamei increased in all the experimental groups, while the malondialdehyde (MDA) contents decreased. Transcriptome analysis identified 5,073 differentially expressed genes (DEGs) for P. vannamei in the T0 and T16 groups. Most of the DEGs are involved in the ribosome pathway, endocytosis, glycerophospholipid metabolism, Wnt signalling, and FoxO =signalling pathways. The majority of the DEGs were from the ribosome pathway, which is also the most significantly enriched pathway. The study confirmed that the growth and immunity status of P. vannamei could improve by increasing dietary TWS119, which probably regulates the activity of the Wnt/β-catenin pathway and may be closely related to ribosome function and energy metabolism.

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