Largemouth bass

[Kens3313]

I have a largemouth bass thats about 5 inches long, in a 50 gal aquarium. Ive had it for about 3 weeks and its been fine and eatting. Ive fed it rosey reds. and some worms. I put two catfish in there and they died after about a week. Well ever since they died the bass has got some cotton looking fungus growing on it. Im not sure if this is ick. Its not white spots really. The bass is a lighter color than before also. Just kinda sick acting, not moving around much and not eatting. Any ideas of what I should do? Thanks