This study investigated the effects of different protein sources and butyric acid contents in aquafeed on the growth, survival rate, lipid peroxidation enzymes, and intestinal villi of 7.3 g jade perch, Scortum barcoo. The experimental treatment groups were the whole fish meal protein (FM) group, the FM + butyric acid (FMB) group, the 50% fish meal protein and 50% black soldier fly meal protein (FBM) group, the FBM + butyric acid (FBMB) group, the whole black soldier fly meal protein (BM) group, and the BM + butyric acid (BMB) group. The experimental results showed that the jade perch fed with the FMB feed had a significantly higher weight gain rate and antioxidant enzyme activity than the other treatment groups. The red blood cell count, hemoglobin concentration, and hematocrit contents in the blood of jade perch were not affected by the protein source, but they increased with the addition of butyric acid. The intestinal villi length of the jade perch that were fed diets containing butyric acid were significantly higher than that of the jade perch that were fed diets without butyric acid supplementation. The results of this study show that the addition of butyric acid to a balanced feed composed of protein can contribute to the growth of jade perch.

This study investigated the effects of substituting fish meal (FM) with black soldier fly (Hermetia illucens) meal (BSM) on the growth performance, body composition, immune response, and antioxidant enzyme activity of juvenile redclaw crayfish (Cherax quadricarinatus). Four isonitrogenous (41%) and isolipidic (11%) diets (i.e., FM substitutes) were formulated from BSM prepared using larvae that were fed soybean meal (BSM-S), fishery byproducts (BSM-F), or pitaya (BSM-P). The experimental diets were fed twice daily to triplicate groups of juvenile redclaw crayfish (0.56 ± 0.04 g). After the feed trial, the FM and BSM-F groups exhibited significantly lower feed conversion ratios and significantly higher weight gain; specific growth rates; and concentrations of saturated fatty acids, highly unsaturated fatty acids, eicosapentaenoic acid, and docosahexaenoic acid in the muscle. Among the tested groups, the BSM-F group exhibited significantly enhanced immune responses and increased antioxidant enzyme activity (i.e., superoxide dismutase, phenoloxidase, and glutathione peroxidase); the BSM-P group exhibited a significantly higher feed intake and hepatopancreatic index; and the FM group exhibited a significantly higher muscle body index and apparent digestibility for the dry matter of crude protein. The findings indicate that the juvenile redclaw crayfish fed BSM-F achieved the highest weight gain among the groups.

A feeding experiment was conducted to study the effects of dietary lipid sources and L-carnitine on the growth performance, body component, muscle fatty acid composition, and antioxidant enzyme ability of average weight of 0.28 g dog conch larvae, Laevistrombus canarium. Three sources of lipid: fish oil, soybean oil, and beef tallow were tested in combination with two levels (0 and 0.5%) of L-carnitine. The dog conch larvae fed diets containing fish oil with L-carnitine supplementation exhibited the highest weight gain. After air exposure challenge, the liver tissue of dog conch fed the diets containing soybean oil and beef tallow without supplemented L-carnitine had lower levels of superoxide dismutase (SOD, U min⁻¹), phenoloxidase (PO, U min⁻¹), and glutathione peroxidase (GPx, mU/mL) activity. The activity of SOD, PO, and GPx of dog conch larvae increased with increasing levels of dietary L-carnitine. In particular, dog conch larvae fed the diet containing fish oil supplemented with L-carnitine exhibited significantly ( ) enhanced antioxidant responses. The thiobarbituric acid reactive substances (TBARS) in the muscle tissue of dog conch larvae fed the diet containing fish oil without L-carnitine supplementation showed significantly ( ) higher activity. It was concluded that dietary administration of L-carnitine can enhance resistance against beta-oxidation, and the administration of fish oil in the diet was the best strategy to promote growth due to high nutritional availability.

This study investigates the effects of dietary supplementation with various carbohydrate sources on the growth and dietary nutrient utilization efficiency of a 0.72-g dog conch, Laevistrombus canarium. Five treatment diets had supplementation with alpha-starch (Sta), dextrin (Dex), pullulan gum (Pg), xanthan gum (Xg), and carboxymethyl cellulose (CMC). At the end of the feeding trial, the best growth performance (weight gain, 442.23%) and diet efficiency (protein efficiency ratio, 1.25, and feed conversion ratio [FCR], 2.04) were exhibited by the dog conch fed the Sta diet, whereas the lowest growth performance was observed in the dog conch fed the Xg and CMC diets. Dog conch fed the Sta (2.04) diet had a lower FCR than dog conch fed the other experimental diets (3.92–5.46). Apparent dietary digestibility (ADD) was significantly higher in dog conch fed the Sta diet than in the dog conch that were fed the other experimental diets. The ADD of protein was significantly lower in the dog conch fed the CMC diet than in those fed the other dietary treatments. The lowest ADD for energy was observed in the dog conch fed the CMC diet, followed by the Xg diet and Pg diet. Moisture, crude protein, and muscle crude lipid were affected by the carbohydrate source. An increase in carbohydrate complexity in the diet led to an enhancement of crude protein content and muscle crude lipid content. Compared with the other diets, the Sta diet yielded a significantly greater improvement in all shell parameters. These findings indicate that dog conch fed a Sta diet demonstrate the best growth parameters, feed efficiency, and ADD; therefore, diets supplemented with Sta are suitable for improving dog conch growth.

Recent studies have suggested that plant‐based proteins, such as algal powder, can partially replace fishmeal used in formulated aqua feeds while maintaining the growth performance of aquaculture species. In Taiwan, the traditional pickled cabbage industry produces high‐salinity wastewater rich in nutrients and microelements essential for plant growth. Reusing this nutrient‐rich brine as a medium for microalgae cultivation offers a cost‐effective and sustainable solution. This study aimed to evaluate the feasibility of using Taiwanese pickled cabbage wastewater (TPCW) to cultivate the halotolerant microalgae ( Dunaliella salina ), and of partially replacing fishmeal in Tripneustes gratilla (TG) feed with the resulting algal powder. The experiment consisted of two phases: (1) cultivation of D. salina using seawater partially substituted with varying proportions of TPCW and (2) assessment of the effects of replacing fishmeal with different levels of algal powder on the growth, survival, and gonad index of T. gratilla (0%: TG0, 30%: TG30, 35%: TG35, 40%: TG40, 45%: TG45, and 50%: TG50). Results showed that TPCW significantly enhanced the growth of D. salina , with the TPCW100 group (100% wastewater) displaying the highest growth rate, yielding 10.07 g of algal powder with 59.6% protein. Besides, a notable CO ₂ decline in late culture stages indicated strong carbon uptake. For T. gratilla , the TG0 group exhibited the lowest weight gain and gonad index among all treatments, while TG40 showed the highest, significantly exceeding TG0 and TG30 ( p < 0.05). Moreover, higher replacement levels of fishmeal with algal powder also increased gonad redness and yellowness, suggesting greater accumulation of pigments such as astaxanthin and carotenoids. Overall, this study confirms that agricultural waste can be effectively recycled for algal cultivation, contributing to carbon reduction, and that algal protein can successfully replace fishmeal in sea urchin feed, enhancing both growth and gonad coloration.