WE had a 55 gal tank given to us and went out and got some fish. Some guppies neon tetras, tetras, and swordtails. All we have left is 2 tetras. They all died and we don't know why. We're afraid to buy more fish now. We've had the water checked and everything seems ok that way. We had cleaned the tank also. We also lately have found a couple clusters of fuzzy white cocoon looking things. We took them out, but what are they? I was so happy to find this site and have people to help.