I recently bought a 20 litre aquarium, and some fish (Comet, Shubunkin, Black moore and two bettas) ive had it for about a week now, but yesterday for some strange reason the comet and shubunkin suddenly started biting the black moore's tail, in the morning it had a beautiful twin one but when I looked at the end of the day, it was all town and the flesh was all in strips, I cant imagine what caused this violent behaviour, as the card said that Goldfish
are very peaceful and community fish. I have separated them for now, but the bowls are small and im not sure they are getting enough oxygen, so I would like any advice on what to do.
Another thing- When I got the tank I also got a betta, but in about a day it died of what looks like fungal infection (white fluff on scales) I tried adding a cure from the shop (bay leaf oil) but it didnt seem to help at all, the betta I have bought now also has this infection, its very strange, two in a row?
Thanks for any advice on this, and sorry if it seems like a stupid question.