Sores on catfish.......

I have been in charge of my daughter's fish tank for the last few weeks as she's moving and not into her new apartment yet. She has a 30 gallon tank with a few tetras and zebra danios. Also in this tank is a big 'upside down catfish' that she's had for several years. A week or so ago it started to get a few small whitish patches on it. It looked like maybe he just got scraped in the move. But now there are many white patches on him, they are growing larger and one looks ulcerated, like an open wound. I have no idea what it is and what to do for him. I would HATE for this guy to die. I've grown quite attached. I am trying to get a photo but he's not cooperating and the glare off the glass of the tank is making it nearly impossible. Any suggestions on how I can get a picture to post for you all or what he may have and how I might help him.

Seriously, I am getting desperate and worried.

By the way, I was a member on here quite a while ago. Great group of folks here, well run forum. It's been a while and I forgot my old user name and password.

Please help me help my beloved fish.

I can't find any medicated food anywhere. I have been putting erythromycin in the tank. It doesn't seem to be getting any worse but I haven't noticed much improvement, either. I noticed he likes to hover next to the heater. Could he be getting too close the the heater and getting burned?

In reading other threads here in this subforum I wonder if I should be using something other than erythromicin. Many recommend a broad spectrum antibiotic. Should I be using something else for my cat fish?

I'll try to post pictures.....

Okay. Thank you so much for your replies. I so want this guy to get better. Actually, this picture is from a couple days ago. The red spot isn't red anymore. I'll get some medicated flakes. I remember years ago the pet shops carried them but I couldn't find them. Of course, I only went to PetSmart and Petco. :irked: I don't really know if he's eating as he usually most active at night. If I wake up in the middle of the night to let the dogs out or whatever, I can see him cruising the tank. In the day he usually just "hovers". But since getting ill he's not been as active at night as usual. Should I stick with the Erythromicin, switch to something else, or quit all meds and do water changes?

Jannika said:

Doesn't look like heater burns to me. Some antibiotics in the water can knock out your biological filter, so check for ammonia. Angels Plus carries medicated flakes, if he's eating. Kanamycin is a good broad-spectrum med.

http://www.angelsplus.com/MedsAntibiotic.htm

Click to expand...

Which medicated flake should I choose? The gram negative or gram positive susceptible one? What makes it so difficult for me is I don't know what he has or what's causing it.