What Am I Dealing With?
I have something going on with my rainbows, but I'm not entirely sure what it is. Initially, it is just the white/hazy patches circled in the photos, behavior and eating habits are normal. Eventually, the patches grow, the fish stops eating and hangs out in a corner at the top of the tank, and (at least in one case) they eventually die. These two are the 2nd and 3rd fish in this tank to develop this issue, the 1st passed. The more "clamped" looking one was starting to act a bit off this morning, the other is still acting completely normal.
I started treatment for columnaris on Saturday using Spectrogram (kanamycin/nitrofurazone), but don't know if that's what I'm dealing with and so far see no improvement, but I've only done 1 of the recommended 3 doses thus far. The tank runs about 77 degrees, ammonia and nitrite are 0, nitrates were 20 prior to Saturday's 50% water change (haven't checked since), ph is 8.3 (which is what it is out of the tap and I don't jack with it). Tank is lightly planted and low tech.
Does anyone recognize this as something besides columnaris and/or have treatment suggestions?