Last month. I heaved up the gravel and i discovered 3 long, almost 1 inche, red like worm. They always hook the other part of their body to the mirror. I got 3 of them. Now, i cleaned again my whole tank. I again discovered worms like what i have mentioned!!!!! I am really shocked because i think i got 25 pieces of them!!!! :x What will i do???? Every week i change 25 percent of the water. i also remove the uneaten food on the gravel. Where did i go wrong??? I really don't want parasites in my aquarium. I visited a nearby petstore and gave me a parasite killer. I put the medications accurately but nothing happened. They get planty every time i heave the gravel. What do ineed to do??? Im really desperate to remove them. :-?