African Rift Lake cichlid, possibly a Protomelas sp or something similar.
How big is the fish?
How big is the tank?
Do you feed them well and do regular water changes?
If the fish is 1 year old and has been fed well and you have done regular water changes, it should be full grown and the adult size will help us to work out what the fish is.
The fish is about 3.75” in a 35 gallon Mbuna tank. If it’s a hap, we need to get a bigger tank and I’m already thinking a 75 but with the mbunas they need chaos tank. I do regular water changes as in 1/2 once every two weeks and 1/3 2x a week with Anubis plants in the tank and a FluvalSmart canister for a100 gallon. Water is pristine as I test weekly witg a master test kit and I feed them north fin, peas, algae red and green, cucumbers, repashy, and zucchini.