Different groups of fish have different dietary needs. That being said, the majority of freshwater tropical’s as well as goldfish can and will eat a staple flake food, or staple pellets if they are larger fish. However, there are many tropical’s that will need food that actually resembles natural prey; in other words they will need frozen food such as brine shrimp, mysis, blood worms, etc. There are also certain tropical fish, especially in the cichlid family, that require a mostly vegetable diet, and so spirulina flakes will be more appropriate. Many bottom feeders will need food that sinks to the bottom of the tank where they live, as they will not have access to floating foods. Giving your fish a well banked variety of different foods will ensure healthy active fish.