http://forum.aqua-fish.net/ A forum devoted to aquarium fish, plants, techniques and fish keeping as a whole. en http://forum.aqua-fish.net/?topic=tiny-critters#1 I have a 30 gallon tank of mollies. There are tiny, almost microscopic critters swimming withing the gravel of my fishtank. Does anyone know what these are? I know they are not fry....They are much much smaller than fry. It is difficult to see them with the naked eye. original post: April 14, 2007, 12:43 am anonymous 2008-05-02 http://forum.aqua-fish.net/?topic=tiny-critters#2 Hi , I know them. They should be kind of tubifex. If you improve the filtration then they will disappear. Worms don’t mean any danger for fish, however they’re seen in poorly filtered tanks only. When I had them in my tank, my bettas were eating them a lot . Peter anonymous 2008-05-02 http://forum.aqua-fish.net/?topic=tiny-critters#3 sounds like they are planaria worms,totally harmless and as posted great free food for you fish mickey 2008-05-08 http://forum.aqua-fish.net/?topic=tiny-critters#4 You lucky one... Live food is very good for fish, but if you want to buy them it is very risky. But when you can rise them by yourself, it is great. Elektra 2009-04-25