I would recommend feeding him more earth worms. Also maybe setup a spare quarantine tank for the goldfish. You can make sure they're disease free, it will save you trips to the store, and you can feed them quality flakes to get more nutrients in them. But ultimately try to get him on Shrimp, Tilapia Fillets, or Silver Sides. Once this is accomplished you can start to gut load his food. But don't give him away!! A 220 should be fine for a while. They don't need as much room as other fish from what I've seen and heard.
Sent from my iPad using
MonsterAquariaNetwork app