What is on my cat?

[Old Man Shea]

Hello all thanks for reading. First off tank. 55 gallon, 80F, ph is 6.5. Nitrites and ammonia and both <25 ppm. And the GH/KH are both relatively low too. Substate is small loose gravel. 50% water changes every month or so.

Problem is on my large Callichthys callichthys. There are what apper to be bumps and bubbles all along the body, and the fins seem to have an extra bit as well. The catfish seems to be more active now with the ailment. I also noticed a slight white slime on my angelfish and after adding a dose of melafix and some salt they seem to be doing much better.
https://picasaweb.google.com/lh/photo/p ... directlink
https://picasaweb.google.com/lh/photo/c ... directlink
https://picasaweb.google.com/lh/photo/F ... directlink

Im sorry I tried to put the images in here but it didnt work

[Taratron]

Looks like a bacterial or fungal infection. I would start improving water quality stat. Try 25% water changes every other day, decrease feeding too.

Ammonia and nitrite should always be about zero in a cycled tank. What are the nitrates?

[Supercorygirl]

I hate to pick but i hope you meant to write WC every week or so...not every month or so. Agree with above comment, and that your cleaning regime is the cause. Hope the fish get better.