Those are most likely sponge eating nudies. They are
small and don't eat much.

Wayne Sallee
Wayne's Pets


StringerBell wrote on 2/7/2007 8:38 PM:
hi,
I recently noticed what seem to be some small mustard colored nudibranchs in
my aquarium. Are these also considered Flatworms? I saw 1 that was about an
inch long. Then there are about a half dozen others that are 1/4 inch or
less.They are kind of cute. I could stand them if their numbers stay low.
.. Are these bad for my tank? If so, what kind of fish would control their
population?
Is it not so much of a coincidence that Ive seen more since I trapped out
the 6-Line Wrasse?
Thanks again-----
Stringer