Why do we need to use artificial feed in pond for fish culture​

Artificial feed is commonly added to aquaculture ponds to enhance growth and survival of juvenile fish. ... Feeding also introduces excessive nitrogen and phosphorus into ponds, which promote growth of nuisance phytoplankton and cause reduced oxygen conditions from aerobic decomposition of feed. Artificial feed is commonly added to aquaculture ponds to enhance growth and survival of juvenile fish. However excessive feeding may decrease fish growth and survival by reducing water quality and natural prey populations.

Explanation:

where in your body is there an enzyme that does function at a high or low ph? what is the name of that enzyme and its function?