infusorias on tank

[danny]

i notice that there are alot of infusorias in my flowerhorn tank.most are cyclops.but there are these worm like organisms.some wriggles freely while some sticks on the glass as they navigate.are these worm like organisms dangerous?or they are just ok?

[Carl]

The description of the worms fit the description of Detritus Worms. These worms are common "composting" worms.
Only if the population explodes can these worms be a problem (generally they can deplete oxygen in high numbers). The detritus worm is often an indicator of too much organic waste.
Beware of of the identification of these worms as Planaria, I see this constantly at YA as an about.com article feeds this myth.

See this article (about 3/4 into the article) for more:
Aquarium Answers; Nematodes and Trematodes, Detritus Worms

Carl