Pleco with blisters

[glolite]

Hi guys. I had a problem with my common plec a few months ago when he came out in blisters. At the time he was in a 45g tank with gravel and an exposed heater. Some peeps on the forums said he may be burning himself on the heater and others suggested the gravel was bad for him. Anyway, he's since moved to a 90g tank with sand substrate and a heater which is integral to the filter. He got better but in the last week has developed large red blisters. My water stats are fine and the sand is stirred weekly. I'm at a loss to know what is causing this and whether or not to treat the whole tank with maracyn 2.
PS he's around 7 inches long and called George.

 

[glolite]

Bump

 

[WILDER]

Are they open sores with red edges.

 

[glolite]

Hi Wilder, no they're closed blisters filled with red fluid. The worst one being on his tail where it joins his body.

 

[WILDER]

I would issolate the fish in case they burst, i would medicate the fish with an internal bacteria med, good luck.

 

[WILDER]

Are they blood spots.

 

[glolite]

They are blisters filled with red fluid. One burst so I'm going to treat the whole tank but I need to know if it's likely to be a gram positive or negative bacteria. I now have maracyn and maracyn 2 which treat either one

 

[WILDER]

Maracyn two, if you can issolate use both, good luck.