Effects of Protein Concentration in Fish Feed on Physical and Chemical Water Pollution

Abstract

Nitrates are linked to higher rates of fish mortality. Fish feces discolors water, reducing clarity and affecting the metabolism of organisms. Food eaten by fish is the main source of nitrates and feces. This work studies how protein concentration in fish feed affects the production of wastes that pollute water. It is hypothesized that high protein fish foods lead to more nitrates, less clear water in addition to an increased amounts of trace amino acids entering the water column. Three experiments were performed to determine which food at a 28%, 36%, or 42% protein concentration contributed most to poor water quality. These tests were performed on feces collected from three species of fish, the freshwater angelfish, koi and the tamasaba goldfish. The tests determined that increasing the protein concentration in fish food did in fact increase nitrate levels in aquariums while water clarity and residual amino acid concentration did not necessarily increase. This is significant because it allows for greater insights into fish feeding which are important for the traditional aquarium hobby and aquaculture farms.