Trainman

Here is an updated photo of the guppy too. As can be seen in the 2nd zoomed in photo, only two bubbles in the dorsal fin are left.

Here are a couple of photos of the neons from this morning.

Update, since I wasn't sure what the infection is, I treated with one dose of the quarantine trio. He was breathing really heavy one the second day and hiding. The rest of the fish all seemed ok. Most of the bubbles are gone, only two are left as of today and they are shrinking. However a platy developed fin rot on day 4 and I isolated it in a quarantine bucket with salt and it's doing well. Now it looks like the neon tetras are starting to have discloration on thier fins. Water parameters haven't changed and I did a 1/3 water change today, as it was 8 days after I dosed the trio. Should I treat with maracyn 2 to address what I assume is fin rot on the tetras or dose the trio again?

What if it was a bubble?

I only realized they were bubbles last night, but I noticed an abnormally a few weeks ago. I had assumed fin nipping, but upon closer inspection, this is what I found.

The fish hasn't been out of the tank. I've attached the same photo cropped to only the bubbles in the center.

My guppy has a bunch of bubbles on his dorsal fin and I can't figure out what this might be and how to treat it. Sorry for the fuzzy photo, but the bubbles are pretty big on the fin, hanging in front of the fish. They appear to be kind of translucent and the same color as the fin. Thanks in advance!! pH - 8 Nitrates - 40 Hardness - ~140 PPM (Not tested, assuming Chicago water #s) https://www.chicago.gov/content/dam/city/depts/water/WaterQltyResultsNRpts/ccReports/CCA-2020-12.pdf Nitrite - 0 Ammonia - 0 KH/Buffer - ~160? Not tested Water Temperature - 78F