I have some catfish, I noticed a few a them have swollen bellies, maybe 10 in 1000 have these swollen and reddish bellies, not sure if it's something to be worried about.
also they are like this before feeding in the morning, the belly never goes down
I'd share some pictures, please let me know if you've experienced similar




I'm going to guess the color is likely from inflammation, the bulge is the real problem here.
And, no I typically don't suggest killing a live animal as a method of diagnosis, but if it's contagious, you could lose more and guessing/shotgun approaches to treatments almost never work.
– Jestep Dec 16 '21 at 17:43