Um my aquarium seems to turn orange for some reason, i have 2 pletos(Cleaning Fishes), 1 Angel Fish, 2 Cichlids, 3 glass fish, 1 ghost black knifefish and 3 albino tiger barbs in a 13 gallon tank.
I have 6x 6″ Silver Dollars and only last night one of them started to move around very strangely. It is doing summer-salts in the aquarium. It cannot stay upright. It starts by struggling up to the surface, flapping about as if not being able to control itself then turns 360 degrees and starts all over again. I have monitored it today and now it is struggling around flapping slowly . I thought it may have eaten something and is slowly choking because my water quality is perfect, I brought a sample down to the local pet shop and got the water tested for everything , nitrates , ammonia etc. I took the fish out and opened its mouth up with a tweezers and I can see straight down its throat , nothing there except for loads of teeth. What can I do? I have never seen anything like this before. The other 5 Dollars , cory catfish , cardinals and other tetras are fine. One other thought , I have these Silver Dollars over 6 years , so maybe its old age. All help and all possibilities needed, Thanks.
I ended his poor life sorry to say.

