Probiotics in Shrimp Aquaculture: A Systematic Review of Effects on Survival and Disease Resistance

Abstract

Probiotic bacteria are now routine additions to shrimp feed and pond water, and they are marketed largely on the promise of better survival and stronger resistance to disease. This narrative review asks how firm that promise is. It draws on published work on the main shrimp pathogens, the mechanisms proposed for probiotic action, the experimental challenge studies on which many claims rest, and the literature on safety and regulation, and it reports no new data. Many studies describe benefit, but they differ so widely in strain, dose, route of delivery, host stage and challenge model that their results cannot be pooled in any simple way. Most trials are short, use small tanks and treat tanks or animals as independent replicates, and a literature made up mostly of positive reports invites concern about publication bias. Protection against a laboratory challenge with one bacterial strain says little about a pond in which pathogens, water chemistry and resident microbes all interact, and probiotics have little plausible direct effect on viral disease. Questions of strain identity, gene transfer and regulatory status receive less attention than they deserve. The review concludes that probiotics are a reasonable and probably useful part of shrimp health management but that the size of their effect on survival is unproven, and it sets out what better evidence would look like.