I have 4 Serpae Tetras in my 3 gallon tank. I know they can get nippy so their only tank mate is a snail. One tetra in particular has issues with his fins, but is otherwise acting normal and all the other tetra seem ok. How can I tell if it's a case of fin rot or fin nipping? There is one fish who is quite bossy, "Mr. Big" who I think is doing some nipping.
I was thinking of putting some melafix into the tank, but I've never used any other chemical of any kind other than dechlorinator so I am hesitant. A long time ago (see post under "I should've known better LOL) I had a (feeder) goldfish and it came down with either velvet or cotton and I put something in the tank (don't remember what anymore) that petco recommended and it killed the fish within minutes. It was awful to watch. Luckily I have not had any issues (knock driftwood) so I'm not prepared without diligent research to put anything in the tank.
(PS: My water parameters are perfect. 0 A 0 Nitri Nitra<5)