Long nose gar fry help!

I am having issues with a gar fry. I can't seem to get him to eat. I'm new to gar fish. He just hangs around the top of the tank all day and stays in one spot. He never really dives down. And when he does he floats back up fast. Maybe a swim bladder issue? I have tried to do the starvation method of pellets and that hasn't worked. I have also tried frozen shrimp. Nothing seems to work. Any advice would be great. He also has 2 tank mates, an Oscar and pleco. Both are young and neither mess with him. The tank is at proper levels. It's a 55gal standard. With quad filtration. I'm currently looking for a larger tank so they will be in a bigger soon. And I know the tank is too smaller for their lifetimes. So please don't bring that up, it's a grower tank. Anyway thanks for the help guys. I really appreciate it.