The feed is eventually turned into nutrients. Nutrients plus light equals algae. Make sure there is just enough food to nourish the fish, Change water more often to flush out the nutrients
We used to have a small business raising fancy goldfish and selling them on the internet. raingarden.us Before that we did aquaculture develpment for the state. There are still some goldfish and pineapple swordtails around here but they're nothing special.