diseased danio?

miagrrl

i have a danio who appears to have something odd going on with his mouth... i can't really get him to stay in one place long enough to make a diagnosis. i initially thought it was that mouth bactertial infection, but it looks more like a bubble, or like his lip is a tad swollen maybe? water quality is a little off (at the tail end of a small diatom bloom), but no ammonia or nitrite, nitrates are 20. he seems to be very active, still has an appetite, still playing with his friends, no clamped fins. is this a wait and see, or should i act now?? i put a little more conditioning salt in the water for now. any possibilites on what it could be?

The-Wolf

danios don't do well with salt.
you say you put more salt in the water, so I'm taking it that you use it as a regular addition.
this is why your danio has a blister, the salt has got into the skin and caused a rection.