Flatworm killers!

[slakker]

I also have peppermint that's suppose to work.. can't say I've seen any eat a flatworm though...

[Delphinus]

I say go for the canary wrasse. Very nice fish in their own right, but mine also took care of my flatworms within a few weeks. At least, I started noticing that I didn't have flatworms anymore a few weeks after getting the wrasse, I assume I had the wrasse to thank for that.

They are jumpers though. Make sure you have a cover or something (even then apparently it's no guarantee, mine found a way through eggcrate earlier this summer).

[truperc]

I have had a Leopard wrasse that ate them. Though they are not the easiest fish to add to an aquarium with any boisterous fish.

[Keri]

+1 on the yellow

[justinl]

canary wrasse for sure. reef safe and peaceful. but as mentioned, a good jumper, just like any other wrasse, so a canopy or lid is mandatory.

[Marlin65]

Mine cleans out other things as well pods, my spaghetti worms are gone, and it has taken out all small snails in my tank. So you have to take the good with the bad.