if you want a good everyday food, get either hikari staple or gold pellet and give them treats several times a week. use freeze dried or frozen foods like tubifex or blood worms, shrimp, plankton.
convicts and firemouths generally arent very picky, so if its made for freshwater fish, chances are your fish will eat it. the more varied of a diet you give them, the better your fish will look and healthier they will stay.
if you really want to give them rosy reds on occasion, be careful of parasites and disease. buy them 2 weeks or so in advance, and keep the rosies in a small 5 or 10g tank with a sponge filter, and make sure to keep the tnak clean and watch for the fish to develop ich or anything like that.
its not bad to give them feeders here or there if their quarenined, since it gives them some stimulation and challenge when hunting, but by far, do not rely on them for anything but a treat and some fun for your fish. give them the pellets and treats as their main diet.
