Bad Guys
Bad Guys

First thing to note: These are not welcome in your tank, if you see them, time to take action!

Though these flatworms will not attack your coral or fish, they can reproduce so rapidly that they can block the light from reaching your corals, which can cause localised bleaching.

They enjoy dining on micro flims, algaes and copepods, but their main source of energy comes from light, they are photosynthetic. They are prolific breeders, and you can soon find your tank over run with them.

Red Planaria
Red Planaria

The are a rusty brown / red colour, and normally no larger than a couple of millimetres in length. They are completely flat, and can be tricky to spot.

The irritation they cause to the coral they are sat on, can cause the coral to close up & sulk, and in some cases bleach out through lack of light.

Red Planaria Flatworms can end up being one of the worst challenges you will ever face in the saltwater hobby, just because of how quickly they multiply.

Another issue commonly found with having these worms in your system is that when a large number of them die, they release toxins into your water column which can kill or harm both your fish and your corals.

How do you control the numbers?

Red Planaria Flatworm

The offence is a good defence when it comes to Red Planaria Flatworms. Dip all corals before putting them into your aquarium, and where possible, quarantine them and monitor them for at least three weeks before putting them into your main display.

If you have found them in your main display, remove as many of them as you can manually. Where you can’t remove them, remove the entire rock in your display tank and treat it with a dip until the flatworms are removed.

A well known and relied upon, reef safe, chemical treatment is Flatworm eXit. I have no experience with Flatworm eXit, so please do your own research before using it in your aquarium.

Do they have any predators?

There are a few relied upon predators for Red Planaria Flatwors. These include:

Blue Velvet Sea Slug
Blue Velvet Sea Slug
  • Six Line Wrasses
  • Leopard Wrasses
  • Target Mandarins
  • Blue Damsels
  • Blue Velvet Nudibranch (Chelidonura varians)

Please be careful adding any livestock to your aquarium. Ensure anything you add you can adequately take care of & that it is compatible with your existing tank inhabitants.

Please do your own research before adding anything to your aquarium.