5.3 Alternative Diets

Alternative diets are a great option to utilize bulk products that are a byproduct of another production system, non-traditional ingredients, or even agriculture scraps. These diets would be prepared on- site and would still be combined in a ratio to meet both the nutrient requirements of the fish and the plant crop. One area where this is seen is in the brewing of craft beer or spirits. The spent grains from the fermentation process (brewer’s grains) typically have a protein content high enough to be used in combination with another protein component, again dependent on the crops to be grown. Also utilized are refuse from animal processing plants, scraps from crop harvest, or even earthworm or other insect sources. One newer insect meal being used is black soldier fly larvae (BSFL). This is an especially good protein source because the larvae can be “gut-loaded,” or fed whatever precursor food would most benefit the fish consuming it, like foods high in Omega-3 fatty acids.

Source: Janelle Hager, Leigh Ann Bright, Josh Dusci, James Tidwell. 2021. Kentucky State University. Aquaponics Production Manual: A Practical Handbook for Growers.