Dietary antioxidant supplementation, especially astaxanthin, has shown great results on reproductive aspects, egg quality, growth, survival, immunity, stress tolerance, and disease resistance in aquatic animals. However, the effects of dietary astaxanthin supplementation from different sources are still unknown. A comprehensive comparison of survival, growth, immune response, antioxidant activity, thermal resistance, disease resistance, and intestinal microbial structure was conducted in dietary antioxidant supplementation from the sources of Gracilaria lemaneiformis (GL), industrial synthetic astaxanthin (80 mg/kg astaxanthin actual weight, named as group ‘SA80’), Phaffia rhodozyma (80 mg/kg astaxanthin actual weight, named as group ‘PR80’) and Haematococcus pluvialis (120 mg/kg astaxanthin actual weight, named as group ‘HP120’) at their optimal supplementation amounts. Furthermore, the SA80, PR80, and HP120 groups performed better in all aspects, including survival, growth, immune response, antioxidant activity, thermal resistance, and disease resistance, compared with the GL group. The PR80 and HP120 group also had a better growth performance than the SA80 group. In terms of heat stress and bacterial challenge, abalone in the PR80 group showed the strongest resistance. Overall, 80 mg/kg astaxanthin supplementation from Phaffia rhodozyma was recommended to obtain a more effective and comprehensive outcome. This study contributes to the discovery of the optimum dietary astaxanthin supplementation source for abalone, which is helpful to improve the production efficiency and economic benefits of abalone. Future research can further explore the action mechanism and the method of application of astaxanthin to better exploit its antioxidant role.

Fermented feed, as a novel type of functional feed, enhances the nutritional value and palatability of feed through microbial fermentation. It effectively mitigates issues such as impaired digestive function, compromised immune response in aquaculture animals, and the over-reliance on fishmeal-based diets. This paper provides a narrative review of the fermented feed, its benefits, its common types, and the factors influencing its efficacy. Furthermore, it summarizes its beneficial effects in aquaculture animals, including growth promotion, immune enhancement, optimization of intestinal microbiota, and improvement in product quality. Despite its considerable potential to reduce costs and improve efficiency, fermented feed faces challenges such as limited industrial-scale production and little research on crustaceans. Future research should focus on database development, intelligent manufacturing processes, and comprehensive economic evaluations to facilitate its broader application in aquaculture.

Macroalgae have long been utilized as a natural feed source in abalone aquaculture. The switch to formulated feeds improves nutritional control while reducing the cost instability of natural feeds. Recently, lipid supplementation has received a lot of attention since it is essential to the early developmental and broodstock stages of aquatic species. The present study aimed to investigate how the growth and reproductive performances of female broodstock Haliotis discus hannai were affected by the dietary supplementation of five lipids: fish oil (FO), perilla seed oil (PO), safflower oil (SO), olive oil (OO), and lard (LO). A total of 500 adult female abalones were randomly divided into five groups (four replicates per group) and fed with five lipid‐supplemented diets for 90 days. The LO group was the worst ( p < 0.05), while the FO group significantly showed the best growth performance, gonad index (GI), fertility, fertilization rate, larvae hatching rate, and larval attachment rate ( p < 0.05). Meanwhile, the FO and PO groups exhibited significantly higher levels of very low‐density lipoprotein (VLDL), vitellogenin (VTG), gonadotropin‐releasing hormone (GnRH), progesterone (PROG), and 17β‐estradiol (E ₂ ) than the LO group ( p < 0.05), indicating their higher ovarian developmental maturity. Furthermore, histological and fatty acid analysis revealed that the FO group contained high levels of polyunsaturated fatty acids such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), which may contribute to ovarian maturation and egg quality. Therefore, the best lipids for improving the growth and reproductive performances of female abalone might be FO enriched in highly unsaturated fatty acids rather than plant‐derived lipids, providing new insights into nutritional research and applications in vegetarian mollusks.

Global warming and summer heatwaves increasingly threaten the survival of cultured Babylonia areolata, but the heat tolerance of different geographical populations and the potential for genetic improvement by hybridization remain poorly understood. In this study, four geographical populations (Thailand, TL; Wanning, WN; Zhao’an, ZA; Changle, CL) and four hybrid combinations (TH, HT, TF, and FT) were compared for mortality rate, median lethal temperature (LT₅₀), and critical thermal maximum (CTMax) under controlled thermal stress. The results showed that the low-latitude TL population exhibited significantly higher LT₅₀ (36.49 ± 0.05 °C) and CTMax (35.77 ± 0.52 °C) than the high-latitude CL and ZA populations (LT₅₀: 35.90 ± 0.05–36.02 ± 0.04 °C; CTMax: 35.12 ± 0.77–35.26 ± 0.53 °C). All four hybrids had improved heat tolerance compared with their low parents, with TH and HT showing the strongest mid-parent heterosis (e.g., 73.68–78.94% for survival at 36.5 °C). However, none significantly exceeded the high-parent performance (TL), indicating only mid-parent heterosis. These findings reveal significant genetic variation in heat tolerance among geographical populations of B. areolata and confirm that cross-breeding can effectively enhance heat tolerance, though it does not produce transgressive superiority. This study provides key genetic resources and a theoretical basis for breeding heat-tolerant strains of B. areolata.

Dietary lipid sources influence growth, tissue nutrient composition, and physiological responses in aquatic animals, but their effects on female broodstock abalone remain insufficiently understood. This study evaluated the effects of five dietary lipid sources, including fish oil, perilla seed oil, safflower oil, olive oil, and lard, on growth performance, foot muscle nutritional quality, digestive-gland antioxidant status, and survival following Vibrio harveyi AP37 challenge in female broodstock Haliotis discus hannai. A total of 500 female abalone were randomly assigned to five dietary treatments, with four replicates per treatment, and fed isonitrogenous and isolipidic diets for 90 days. Results showed that the dietary lipid source significantly affected growth, foot muscle crude protein and lipid contents, amino acid and fatty acid compositions, and digestive-gland antioxidant status. The fish oil group showed the highest measured total amino acid and taurine contents and docosahexaenoic acid (DHA) proportion in foot muscle, together with the highest observed final survival after V. harveyi challenge. Perilla seed oil and olive oil warrant further evaluation as alternative supplemental lipid sources under the present experimental conditions. These findings provide useful information for lipid source selection in formulated diets for female broodstock abalone.

Water exchange is linked to survival in aquaculture, but its relationship with host–environment microbial interactions remains unclear. We aimed to characterize host-associated and environmental microbiota in Babylonia areolata (ivory shell) aquaculture, focusing on community relationships, environmental source contributions, associations with water quality, and host survival across water exchange rates. Ivory shells were reared for 60 days at high (100% d ⁻¹ ), medium (50% d ⁻¹ ), and low (0% d ⁻¹ ) water exchange rates. On day 60, water, sand, intestinal, and gill samples (12 samples per treatment) were profiled using 16S rRNA gene V3-V4 amplicon sequencing. The results showed that survival was lower only in the low-exchange group ( p < 0.001). Analysis of similarities (ANOSIM) showed that the host microbiota differed significantly from environmental communities (R = 0.739, p = 0.001). SourceTracker identified sand as the largest environmental contributor; its contribution declined from 48.0 to 21.0% in the intestine and from 65.7 to 30.2% in the gills as the water exchange rate decreased. Reduced water exchange rates were also associated with declines in the relative abundance of intestinal Nautella and gill-associated Ruegeria . Linear discriminant analysis effect size (LEfSe) identified Halodesulfovibrio as a shared biomarker in both tissues under low water exchange conditions. Redundancy analysis (RDA) identified NO ₃ ⁻ -N and pH as the environmental variables most strongly associated with environmental microbial community structure. Exploratory genus-level correlations showed that rearing water pH was negatively associated with Halodesulfovibrio in both tissues. Collectively, these results indicate that the water exchange rate is associated with host-associated microbial community composition, environmental source contributions, and ivory shell survival. Future studies should investigate the mechanisms underlying the associations among environmental microbial communities, water quality conditions, and host survival, thereby informing microecological management in low water exchange aquaculture systems.