I have a 20 gallon tank. We went on vacation for a week, the in-laws extremely overfed our fish. The fish weren’t fat or anything the water was just a horrible dark brown. I did water changes until it was clear again. Took care of the tank for a week, and then had to go out of town for 2-weeks. My wife fed the fish during this time. For some reason half of the fish died, and one of our snails died. One of the fish that died after I came back was ballooned up to about 3 times his normal size. None of the other fish that died balloned up like this. None of my x-ray tetras have been showing any signs of being ill, its been the other fish so far. Except now one is having trouble floating, he’s always sinking, still swims around and eats though. I’ve been feeding them a varierty of sinking food, flake food and every now and then brine shrimp.
Ammonia, Nitrite, and Nitrate levels are all fine, and this is an established tank. Could there be something wrong with my tank?
I want to add fish, but I don’t want to possibly put new fish into a sick tank.
I’ve thought about adding some sort of medication (suggestions?) to the tank but I’ve heard some of those wipe out the good bacteria in the tank too, and I don’t want to do that if its not necessary.
I do use aquarium salt in the tank.