Chemicals we use in aquariums specifically state "not meant to be used on fish intended for human consumption". Take that as you will.
In a 240g you could probably get away with a largemouth but keep in mind they average out at 18" and can grow much larger. Bluegills, pumpkinseeds and bullheads (mudcats) are all great aquarium choices and won't outgrow the setup. I've never kept crappie but I'm told they can be difficult and unlike the other fish you mentioned are more difficult to convert to prepared fish food. Whatever you choose I suggest aiming for younger fish as they'll adapt better to the aquarium lifestyle and will be easier train on to dry foods.
In a 240g you could probably get away with a largemouth but keep in mind they average out at 18" and can grow much larger. Bluegills, pumpkinseeds and bullheads (mudcats) are all great aquarium choices and won't outgrow the setup. I've never kept crappie but I'm told they can be difficult and unlike the other fish you mentioned are more difficult to convert to prepared fish food. Whatever you choose I suggest aiming for younger fish as they'll adapt better to the aquarium lifestyle and will be easier train on to dry foods.
