I didn't post this in the betta related threads because his tank had plattys a sucker fish and guppies. But man, let me explain this situation to you.
We are both really inexperienced fish keepers lol.
He has a 55 gallon fish tank. I know for a fact that it has not be changed at all, what so ever for over a year. He lives with his grandparents who are too old to care for a tank of that size and he is a very busy working college student.
He did have a pirana that we assume died of old age because he had it for a long time.
Maybe a month or two after the pirana died, he got 4 plattys. They all died shortly after. And during this time his tank turned a milky color for a few days and then it cleared up. I'm guessing that was a bacteria bloom due to the new fish being in there.
After the platys died he got 4 guppies, 2 males, 2 females and about 20 tiny snails. They lived for a about 3 weeks and then we decided to buy a gravel vaccum and clean out the massive amounts of algae from the tank.
I sucked up a lot of algae and we never used a gravel vaccum before so we didn't know how much water would have been lost. His grandpa took the outdoor hose and but it thru the window into the tank to keep it from emptying out while vaccuming the gravel. The fish were still in the tank during this. The pet store worker said this would be okay. We added water treatment periodically while the tank was filling up/emptied out.
I was skeptical of this and sure enough all the fish besides from the sucker fish died that night. But before we clean the tank, the female guppy had a white string hanging from its belly for a few days. We weren't sure if it was a parasite or a worm. I suppose we won't know now.
They have had the same filter for a longggg time now. I rinse and clean everything in it. But we still never a new filter pad. I told him to not get anymore fish until the tank is ready, but his grandparents came home with some more fish. Bigger ones, Some sort of shark and catfish. I dont know the exact names.
I'm just worried because I know the tank is very unstable and there could be a change that there could be parasites in there. UGH! what should we do? I would hate for more fish to die.