Hi, I have a dwarf oto with a very red head. It has been a bit red for some time (about a month) but the redness has suddenly spread and become quite big. All other fish seem fine.
Tank stats:
Amonia 0
Nitrates 0
Nitrites 0
26 litre tank
79F / 26C
Fish:
3 Zebra Danios
1 Dwarf oto
1 Kuhli loach...