[iasuka]

Hello!

I am start thinking my shrimp population are less have to do with it. Alot of time I saw freshly dead shrimp was cover hundred of them. But most of the time you don't really see these guys. They are no longer than 1/2 inches and very very thin.

Hmm, sounds like planaria to me. Please look at this macro picture: http://www.aqa.ru/photos/details.php?image_id=20764

If it looks familiar - you may be in trouble. Planarias, although small, are predators, they hunt small shrimps and fry. Some people even report them attacking Malawi cichlids. Fish generally don't eat it, because they taste awful.

I've had planarias in my 10 gallon shrimp tank last year and managed to get rid of them only by most drastic measures: I boiled gravel and bleached tank and aquarium tools.

Best regards.