I have an 18 gallon aquarium with 2 Goldfish, common and a fantail. They are about 1 1/2 years old now (or since I got them from the petstore) The tank used to get REALLY green all the time, not the plants and rocks just the water. We finally figured out that is was the florestent light on top acting like sunlight and causing the algea to grow. I cleaned the entire tank and let it run for a day, then put the fish back in. It has stayed really clean (thank God) and the fish were fine until about a week ago. When I feed them they swim out up to get their food and dart around like happy little fish. But the rest of the day they sit on the bottom together, not moving, just sitting there. I have never had a fish do that before... Am I doing something wrong? They are eating Omega One freeze dried Tubifex Worms