Agree on sandperch. Sandperches are sea fish with an elongated cylindrical body. They form part of the family Pinguipedidae and live around the Indo-Pacific areas and generally warmer waters. They aren't particularly social or predatory fish and like to hide amongst the sand. They are often used as bait for larger fish in the wild and in the tank can stir up sand.
with similarities to squirrelfish, they should eat meaty foods regularly