Vary the food. Sinking pellets, meal worms, blood worms, krill, etc.... If your going to do feeders be extreamly careful and keep them quarentined/treated for a while to make sure they don't have any disease before you put them in with your catfish, especially untill he is fully healed and back to normal. If he hasn't been doing well he will be even more seceptible to disease. They eat a ton so that is another thing that you will have to be preparded for. The amount of money it take to feed a fish like this when it grows is no laughing matter.
I know that he is cute and it's very tempting to keep him but aside from just getting to be huge he's hopefully going to live a long long time. I know that sometimes people can get something not knowing what they have and can really change what they are doing and work to accomidate it but that is not a typical situation. You really need to make sure that you know what your in for. Your kinda young too, please don't take that a a dis, it's just that a lot will likely change for you over the next several years and these fish are extreamly hard to take care of. If you own your own house where your can build a pond and you have a full time job to fund a fish like this they can still be hard to properly care for. Please please make sure that you really want to take care of this fish and that you know what your in for, we keep saying this only because we love fish and don't want to see anyting happen to him. Since your still living with your parents they should know what they are in for as well. What happens as this fish starts to grow and your parents don't want a pond in their house? It's a huge responsibility....