Pacific sardines One of the prime issues facing aquaculture is its dependence on wild fisheries for fishmeal and fish oil, which are used to feed many farmed species. The high cost of fishmeal and fish oil—as well as their limited availability—is encouraging the development of alternative feeds. Potential alternatives being tested or in use include soy, grains, other plant proteins, single-cell proteins, algae and byproducts from seafood and livestock processing. Many of the major feed manufacturers are investing heavily in development of these products.