A few months ago, I had a Planaria problem in my fish tank.


The neon tetras didn’t seem at all interested in eating them. It got me worried and I obviously started googling about what to do. Do other fish eat Planaria? Some people reported that Celestial Pearl Danios will eat them. Others recommended a de-worming medicine.

One of my local fish stores had Rainbow fish in stock. I decided to take a chance and add them to the tank.

The very next day, I couldn’t find a single worm in the tank. Apparently the rainbows gobbled them all up!

Since fish-keepers rely on each others’ experiences, I just thought I’d write it down.

  • The planaria were most likely introduced in the tank when I previously added some shrimp and otocinculus. I don’t think they just “appear” out of nowhere due to poor tank conditions.
  • My shrimp population died out. The planaria must’ve been preying on them. (I’ve never had good luck with shrimp).
  • There were probably a dead fish or two beneath the driftwood that I could never find that made the planaria population increase significantly.
  • Rainbow fish almost certainly will eat planaria. (I’m not a 100% sure because I didn’t really watch them eat)

Another interesting thing that happened was that my pest-snail population started reducing after introducing the Rainbows. Maybe the Rainbows are really good at finishing off leftover food? But I wouldn’t be surprised if they go after snails (or snail eggs) too. I’ve seen them picking on snails on the glass, but they just let it go and not actually eat them.

Rainbows are really cool fish!