This study investigated whether these contrasting environments are associated with the development of coherent, organism-wide phenotypic–physiological syndromes reflecting a fundamental life-history trade-off. A controlled 60-day trial was conducted comparing crayfish from a high-input pond system (fed to satiation) and a low-input rice paddy system (primarily natural diet). Pond crayfish were fed a commercial formulated feed twice daily to satiation (approximately 3% of biomass per day). Rice paddy crayfish primarily consumed natural food webs and received a once-daily supplement of 30% of the pond feed amount (approximately 0.9% of biomass per day). Results revealed two distinct syndromes. Pond-cultured crayfish exhibited a growth-oriented syndrome: they were 33% heavier with a compact, volumetrically enhanced body shape, coupled with elevated lipid-anabolic enzyme activities (lipase and ACC), higher hemolymph protein and cholesterol concentrations, but also significantly increased levels of a stress-related endocrine factor (cortisol-like immunoreactivity) and oxidative damage (MDA). Conversely, rice paddy-cultured crayfish displayed a stress-resistance-oriented syndrome: a streamlined, deeper-abdomen morphology, fortified antioxidant (SOD, CAT, and GST) and immune (lysozyme and phenoloxidase) capacities, enhanced carbohydrate digestion (amylase), and lower systemic stress. Transcriptomic analysis showed that the hepatopancreas of paddy-cultured crayfish was enriched in pathways related to lipid metabolism, detoxification, and endocrine regulation, notably with upregulation of the SULT1E1 gene. Our findings demonstrate that the distinct environmental and nutritional conditions of each aquaculture system are linked to specific multi-level adaptation syndromes, presenting a clear trade-off between rapid biomass production and systemic stress resistance (within the 60-day trial period), providing a mechanistic basis for optimizing sustainable practices: integrated systems enhance stock robustness, while intensive systems require strategies to mitigate physiological load.

This study evaluated the effects of feeding juvenile southern catfish (Silurus meridionalis) with one of six isonitrogenous and isoenergetic diets where fish meal (FM) was replaced by black soldier fly larval meal (BSFLM) at 0%, 10%, 20%, 30%, 40%, and 50% levels on growth, muscle quality, antioxidant capacity, immune response, and gut microbiota of juvenile southern catfish (Silurus meridionalis). A total of 1620 fish (9.20 ± 0.15 g) were fed one of six experimental diets for 8 weeks. Results demonstrated that a 50% replacement (H50 group) significantly improved weight gain rate, specific growth rate, and protein efficiency ratio (p < 0.001). Antioxidant capacity (T-AOC) was enhanced in groups H30 and H50, while immune markers lysozyme (LZM) and alkaline phosphatase (AKP) showed mixed responses. Muscle texture properties such as chewiness and adhesiveness were significantly altered across treatments. Gut villi remained structurally intact in all groups, and liver histology appeared normal. No significant differences were found in muscle amino acid or fatty acid profiles. Gut microbiota analysis revealed shifts in microbial composition, with increased abundance of Clostridia and Escherichia and functional enrichment in metabolic pathways at higher substitution levels. Interspecies network analysis indicated potential cooperation among beneficial microbes through metabolite exchange. It is concluded that 50% BSFLM substitution optimizes growth performance, muscle quality, and antioxidant capacity, while modulating gut microbiota, indicating its promise as a sustainable FM alternative and functional ingredient in aquafeeds.

The genus Pseudobagrus represents a group of economically and ecologically significant freshwater bagrid catfishes in East Asia, yet its taxonomy remains contentious. This study employed the complete mitochondrial genomes of 15 Pseudobagrus species to clarify their phylogenetic relationships. The mitogenomes ranged from 16,526 to 16,647 bp, exhibiting a conserved gene order and significant AT bias (average A + T = 57.85%). All genomes contained 13 protein-coding genes (PCGs), 22 tRNAs, two rRNAs, and a control region. Start codons were predominantly ATG, except for COI (GTG), while stop codons varied among TAA, TAG, and incomplete T--. Codon usage bias favored NNU and NNA codons, and 12 optimal codons were identified in P. albomarginatus. The phylogenetic trees based on concatenated PCGs revealed two major clades. Clade I contained 14 species. Within this clade, P. albomarginatus, P. tenuis, and P. brevicorpus clustered together first, and then this trio grouped with P. ussuriensis. Pseudobagrus trilineatus formed the separate Clade II. These results provide a molecular foundation for species delimitation and systematic revision within Pseudobagrus, supporting the monophyly of the genus while highlighting cryptic diversity and taxonomic complexity.

The red swamp crayfish is cultivated in intensive ponds and integrated rice–crayfish systems, which drive distinct growth-oriented versus stress-resistance syndromes, yet their metabolic underpinnings are unclear. We applied untargeted LC-MS metabolomics to hepatopancreas from both systems. Among 2681 metabolites, 566 were differentially abundant. Pond-cultured crayfish exhibited a lipid-centric anabolic metabolome (enriched ceramides, lysophosphatidylcholines, and free fatty acids) that supports rapid growth but incurs oxidative stress. Conversely, rice-paddy crayfish showed enhanced purine metabolism, aminoacyl-tRNA biosynthesis, and D-amino acid metabolism, reflecting energy mobilization and protein turnover under limited resources. Targeted assays confirmed significantly higher GSH/GSSG ratios (11.29 vs. 5.07) and lower MDA (3.07 vs. 5.00 nmol/mL) in rice-paddy crayfish, validating transcriptomic upregulation of glutathione biosynthesis. Integration with transcriptomic and phenotypic data revealed coherent trait–metabolite modules. Our findings suggest a trade-off between biomass production and systemic stress resistance, mediated by differential activation of purine and glutathione pathways, consistent with a growth–defense trade-off framework. This provides a mechanistic framework for sustainable aquaculture: integrated systems enhance robustness, whereas ponds require strategies to mitigate physiological load.