worms

[fishfan04]

i have recently noticed little worm-like creatures in my tank. they seem to only come out when the light is off. they swim to the surface by spinning and then crawl around on the sides of the tank. they are all around 1 cm long and are not very visually pleasing. does anyone know what these are?

 

[ostrow]

not enough info. how long? color? shape?

generally I like all the critters. but if they are, say, flatworms this is very bad.