Contrasting effects of short- and long-term starvation on intestinal health and gut microbiome in yellow cheek carp (Elopichthys bambusa).

Starvation is a common stressor in aquaculture that can markedly affect intestinal health and function in fish. This study focused on yellow cheek carp (Elopichthys bambusa, initial body weight: 221.36 ± 6.75 g; initial body length: 28.47 ± 0.56 cm) to explore how short-term (8 days) and long-term (28 days) starvation influence intestinal morphology, expression of key functional genes, and gut microbiota composition. Additionally, Spearman's rank correlation analyses were conducted to explore potential host-microbe interactions. The results showed that short-term starvation did not significantly affect intestinal muscle layer thickness or villus height, but markedly upregulated genes associated with autophagy and apoptosis such as bcl-2-associated X protein 2 (bax2), bcl-2-like protein 1 (bcl2l1), and cysteine-aspartic acid protease 8(casp8). It also increased microbial diversity and altered the composition of dominant gut microbiota. In contrast, long-term starvation significantly suppressed the expression of copper/zinc superoxide dismutase (Cu-Zn sod), casp3a, and casp9, increased the number of goblet cells, inhibited muscle layer development, and weakened the correlation between gut microbes and host gene expression. In summary, short-term starvation appears to maintain intestinal homeostasis through activation of autophagy- and apoptosis-related pathways in conjunction with microbial restructuring. However, prolonged starvation inhibited muscularis development, increased goblet cell density, downregulated antioxidant and immune-related gene expression, and weakened the associations between the host and its microbiota. These findings provide new insights into starvation-induced physiological responses and contribute to gut health management strategies in aquaculture.