I used to have a 10 gallon. Once a month (or is it every 2 months), you should drain it and rinse the gravel in strainers (put the fish in bowls, obviously). Change the filters etc. Fill the tank, condition the water. Let the fish get accustomed again in plastic bags. Ummm. That's about it. It's more work than people think. I never could keep Black Molly's; they always got that white fungus, so I stopped getting them. Just make sure the temp. is right and keep alert for fungus and disease and keep on top of it (meds.). I loved my fancy guppies, tetras, etc. I had a few bouts of illness and lost some fish along the way. But my "sucker" lasted throughout it all and grew to be a big fat SHARK! LOL. Now I want a tank again...