Dunno why that would be a case this tank has been lightly stalked for months until I removed the 4-5 fish that were in it and placed the colony into it and I do 50% changes on this tank weekly. This tank has a fluval 406 / a large sponge filter / a submersible filter good for 40 gals as well. There’s no reason for ammonia build up. And it’s onky my hifin green phantoms showing this my blue phantoms aren’t and neither is the single vampire pleco that’s in there
The spots are going away I left the water unchanged for 3 weeks then did a few 10% changes every day for 4 days then let it sit on the 5th then did a 50% and the spotting has gone away mostly. I think it was stress of new tank and slightly different ph as I dropped the ph slightly to more of what they re use to naturally as they re wild caught. When I got them I placed them in a quarantine tank I had for some cichkids which had a higher ph.