Some kind of cloudy mold or fungus growing in my QT

[annewaldron]

I'm on my second round of antibiotics (Maracyn 1&2) for some kind of bacterial infection that my flame tetras have. I'm three days in on the five day course, and I see only slight improvement so far. 8 of the 9 look fine, but the largest one just doesn't seem to be shaking whatever he's got. (Pics attached. Whitish patches beneath the region of his dorsal fin, and most noticeably right next to his tail fin)

But that's not really what I'm worried about. There is white fuzzy stuff starting to grow around the sides of the tank. Pics attached

I'm running an Ovation 700 in my 10 gal QT with new established filter media put in before this round of meds, daily ammonia tests are coming back 0, although nitrates are dropping, so I'm expecting the cycle to crash here before long.

This morning I double-rinsed/soaked a clean cloth in dechlorinated water and wiped up the worst of it (keeping in mind that there's beneficial bacteria in there too, so I didn't wipe down the whole thing) I took out the filter media and rinsed in dechlorinated water, took out the heater and cleaned it off.

Should I be concerned about whatever this crud is that's growing?