Its a burundi frontosa, if he was incorrectly labeled and sold to you, not sure what size tanks you have/what you know about frontosa but he will need a larger tank when older he/she can get 12 inches (+/-, some can get larger and some don't get quite as large) so you might want to keep that in mind. If you already knew then awesome. They are pretty cool little fish. As for sexing it, venting it would be the best way to find out the sex. Fronts usually tend to be more on the docile than aggressive side, though they do lip-lock and fin nip. They usually do better in colony's and if they are with fish more aggressive than them they tend to stress out.
