Just trying to help here (along with nabbing my first triple in quite some time);
As a rule of thumb contaminants are deposited in fatty-tissue areas, the more fat a fish has, the higher the contaminants. Panfish (Crappie, Bl00Gill,Etc) have little to no fat. Bass/Saugeye - Moderate Fat levels (depending on the season). Catfish - high fat, basically all year.