can I keep a dwarf lion with a cowfish? I know the lionfish swallows anything, but the cowfish has protection! has anyone tried this? also, will they be god in a 55G? thanks.

as long as the cowfish doesn't fit in the lionfish's mouth they should be fine together.
A 55g tank should be ample for them.
The only thing you will find is the cowfish has a small mouth and will need small bits of food. Whereas the lionfish will take bigger pieces.

Umm, I wouldn't and not because I was worried about the cowfish, but because I was worried about the lionfish... When scared or startled, Cowfish can/do release deadly toxins into the tank which can kill all kinds of marine organisms and quickly lead to a tank crash. IMO Cowfish belong only with peaceful tank mates and really shouldn't be kept by people who aren't willing to risk the total loss of their tank.

Lionfish are peaceful enough, but the tank size and, as above, the potential for toxicity both worry me here. Cowfish get pretty big, a fifty-five isn't going to be enough long-term in my opinion. It would be best to replace the cow with a filefish or mellow puffer.

yeah, i was going to set up a 55G, but since i like to keep my fish happy i will just wait until i get a 100+. thanks for all you help!