New fish problem
I'm still new in being a fish owner. I has two other tiger fish & another cichlids fish. They are healthy & happy. This morning my levels of ammonia were zero and the nitrate & nitrate are also at zero. Did couple of water changes last month due to nitrate levels a bit high. Well today I bought a tiger fish at Petsmart and he's dying, one of his eyes looks like is gray and his skin looks horrible and will be dead in about an hour. What did I do wrong? What should I be looking for? And can my other fish get sick from this dying fish?