Patrick12
Crypt Assassin
Sounds like you may already have an idea about this, but make sure that your are primarily feeding crabs or fish that are of marine source origin. If they are not, they will be deficient in omega fatty acids and will over the longhaul, be nutritionally poor for your fish. Only saltwater sources are going to be sufficient in nutritional quality because they will have either fed directly or indirectly on the plankton drift. Freshwater fish and inverts are bad to feed to marine sources simply because their diet is so different.