Sources of protein diet differentially stimulate the gut and water microbiota under freshwater crayfish, marron (Cherax cainii, Austin 2002) culture

To reduce the reliance on fishmeal (FM), other protein sources have been evaluated on cultured animals. In a 60‐days feeding trial, marrons (Cherax cainii) were fed a FM diet and five test diets containing 100% of plant‐based protein sources such as soybean, lupin and valorised animal‐based proteins such as poultry‐by‐product, black soldier fly and tuna hydrolysate. At the end of the trial, DNA samples from marron gut and rearing water were investigated through DNA‐based 16S rRNA gene sequencing. Plant‐based diets increased abundance for Aeromonas, Flavobacterium and Vogesella, whereas animal and insect proteins influenced diverse bacterial groups in the gut linked to various metabolic activities. Insect meal in the water favoured the growth of Firmicutes and lactic acid bacteria, beneficial for the marron health. Aeromonas richness in the gut and reared water signified the ubiquitous nature of the genus in the environment. The higher bacterial diversity in the gut and water with PBP and BSF was further supported by qPCR quantification of the bacterial single‐copy gene, rpoB. The overall results suggested that PBP and BSF can exhibit positive and influential effects on the gut and water microbial communities, hence can be used as sustainable ingredients for the crayfish aquaculture.