I just noticed one of my cardinal tetra lost 1/3 of his (her) tail fin. We just cleaned the tank on last Friday with 40% PWC. (0, 0, <10)
It is hard to believe to have fin rot and/or fin nipping in our community tank.
Size: 36G Bow
Fishes: 2 Male Guppies, 9 Rasboras, 5 Neons, 2 Cardinals...