Earthworm Powder Mitigates Soybean Meal Induced Growth Inhibition in Rice Field Eel (Monopterus albus) by Regulating Appetite and Improving Intestinal Health

The substitution of fish meal (FM) with soybean meal (SBM) is a sustainable strategy for the aquaculture industry, but it often leads to reduced feed intake and poor growth in farmed fish. This study aimed to evaluate whether adding earthworm powder (EP) to the diet could mitigate these negative impacts in rice field eels (Monopterus albus). Our findings indicate that while high levels of SBM suppressed appetite and damaged the gut, the inclusion of 2.5% EP effectively reversed these effects. EP was found to stimulate the eels' feeding behavior by regulating brain signals and hormones, while simultaneously repairing intestinal tissue, strengthening the gut barrier, and balancing the community of gut bacteria. These results suggest that EP is a promising, natural feed additive that can support the use of plant-based proteins in aquafeeds, thereby promoting the health and sustainable farming of Monopterus albus.