brown flatworm

[ConsultantERP]

I seem to be getting some kind of flatworm around the base of my live rock. They also look like the brown cynobacteria but on closer inspection they look like a rectangle with each corner pulled out. I guess I have 2 questions. Do I need to get rid or somehow control them (I have alot of them), and if I need to get rid of them, how.

 

[VaderWS6]

I had an explosion of those flatworms about 8 years ago, and the species was more of a nuisance than detrimental. Luckily I didn't have the species that feed on soft corals. If you take a few of them out and place them in freshwater, you'll notice that they burst into a brown liquid and die. Usually they appear due to overfeeding or heavy nutrients, and I think there is a photosynthetic species as well. When they die, they release a toxin, so a mass extermination may not be a great idea. There are some species of wrasse that feed on them, but the velvet sea slug feeds almost exclusively on them. Velvet Sea Slug If the population grows too large, they may begin to cover coral thus blocking light. Just siphon out as many as you can with water changes to keep their numbers in check. They should magically disappear within a few months/year though.