I recently went to an auction and picked up a bag of 3 juvinile red head tapajos but one of them is either surinamensis or altifrons. The fish is about 2.5". How do I tell the differance between the two?
Altifrons usually have a very small (or nonexistent) midlateral spot. It's one of the first give-aways when you look at them. Also, true surinamensis don't seem to pop up very frequently in the hobby, so it'd be random to get one from an auction where it wasn't clearly labeled as such.