The subject invention provides microbe-based products, as well as their use, for enhancing aquaculture. In particular, the subject invention provides materials and methods for producing healthy and high quality farmed fish by applying yeast and/or bio surfactant-based compositions to a fish farm. In one embodiment, the subject invention improves the environment in which the fish are farmed. In another embodiment, the subject invention provides a highly nutritious fish feed, as well as methods of feeding fish at low cost.