Worms in the aquarium

Originally Posted by Jim K

I need some help identifying worms in my aquarium. My tank is heavily
planted, and I recently found some worms moving along the substrate. They
are reddish-brown, about 2 inches in length and 1/8" in diameter. I would
supply a photo but they disappear very quickly.

My questions a

1. What are they?
2. Where would they have come from?
3. Are they harmful to the fish?

Thanks in advance.

Those are planaria worms. They won't hurt your fish, but they are a sign of overfeeding, or having too many nutrients in your tank. You need to vacuum the gravel really well for several days in a row to get rid of any uneaten food in it and stop feeding your fish so much.

The tank with the Oscars is a bit of a problem because you can't add any small fish to eat the worms that won't get eaten by the Oscars and feeder guppies or goldfish that might eat the worms might have diseases that would be passed along to your Oscars if they ate them. I'd say your best bet is to try to starve them out. Feed your fish tiny amounts and make sure they eat every speck of the food. Keep your tank water very clean with water changes and thorough vacuuming of the substrate and the worms should go away.

If you don't feed the fish in the tank with the tetras and angels for several days, the fish should eat the planaria worms and get rid of them fairly quickly.