Terrible Advice Tuesdays: If you have a red planaria (a type of flatworm) problem, add a mandarin to your tank. The trick though is to add a female mandarin as they go after the flatworms more aggressively than males.
The rest of the story: This terrible advice has two parts, so let’s break it down:
Part 1: A mandarin will eat flatworms. I’ve come across some circumstantial evidence that mandarins will eat flatworms. The key word here is “some”. For every person who says their mandarin eats flatworms, there was easily 3 or more people who said their mandarin doesn’t touch them. Here’s the really terrible part of this advice: you won’t know if the mandarin will eat flatworms until you add it to your tank. If it does it flatworms, once the flatworm population is gone, then what? Maybe, maybe, the mandarin will switch to eating frozen food. I’ll assert that a mandarin suddenly making a switch to frozen food is twenty times less likely than a mandarin eating flatworms. If the mandarin doesn’t spontaneously switch to frozen food then you’re left bombing your tank with pods to try to keep the mandarin alive. And no, the small refugium that is part of your sump won’t produce enough pods to keep the mandarin alive.
Also, once the flatworms are gone, you’re not going to go dump more flatworms into the tank to feed the fish! The whole reason for getting the mandarin in the first place was to remove the flatworms!
Part 2: Female mandarins will more aggressively eat flatworms than male mandarins. This part of the advice sounds like circumstantial evidence taken to an extreme. Some hobbyist likely had a pair of mandarins and the female happened to eat flatworms while the male didn’t. The conclusion? Having a female mandarin is the key.
If you have a red planaria problem, I recommend an arrow crab or a Hoeven’s wrasse (Halichoeres melanurus). Yes, both of these animals may, or may not eat flatworms. If they don’t, the arrow crab can easily be removed and the Hoeven’s wrasse will eat frozen food very easily. Disclaimer: Hoeven’s wrasses sometimes eat clean up crew members such as shrimp and crabs. I’d rather have you lose your clean up crew than take a risk on a mandarin eating flatworms.
Finally, I’m not a fan of medicating your tank to remove flatworms. These medications will likely kill the flatworms and when the flatworms die, they can release toxins that can poison your tank.Browse the Store! Questions?