Hi
@AndresDavis
You are right to be concerned about polluting the tank water. Many processed fish foods contain a high level of phosphate but the manufacturers rarely, if ever, disclose this information. As Darrel (
@dw1305) suggests, it is probably best to use live foods. Failing that, have you considered frozen foods? There is a good choice - Daphnia, Cyclops, Brine Shrimp, etc. You should be able to obtain these from your LFS. It goes without saying that some fish are 'meat-eaters', some are herbivores, etc. In order to determine the correct choice for your fish, I suggest you take a look at:
seriouslyfish.com
JPC