I'm thinking Tanganyikan cichlid. I've done a lot of research into them recently (setting up a tank for multies). It's body shape and pectoral fins are perfect for a shallower water (possibly shell dwelling) cichlid. It might not be a Tang but it's definitely part of the cichlid family. I'll eat my hair if it's not.
Group with 1 male 3+ females, hard water, rocks and pebbles and sand/small gravel for them to dig in and most of all, shells for them to live in. Apple snail shells work lol.
Thats pretty much all there is to them, they'll live and breed happily.