Mystery Worm

Question

Mystery Worm   I have a 75 gallon freshwater tank that was started 2 months ago. I upgraded from a 45 gallon tank. I used the same gravel, bio material, and ornaments from the previous tank. The 75 gallon tank is acrylic and was used as a saltwater tank (don't know if that's important). My fish are healthy and breeding.  However, yesterday when I was cleaning out my refrigum... I noted this worm in my filter media. It's a small 4-6 mm segmented-ish worm. It looks like the worm is a gray color. I think you can see it in the image. Oh, and I do not feed live food to the fish.  My question... what is it and is it dangerous? I am a bit worried. I have never seen anything like it in a tank of mine before.

Answer
Rose,
It looks like a Annelid.n These are usually harmless to the fish as long as they are no eggs. Most worms found in the tank are caused by over feeding and no doing weekly water changes. If this is the only one you found, you should be ok. If any get into the water, the fish will most likely eat them. Make sure to remove all uneaten food after two minutes and do weekly water changes with a good gravel cleaning and you should be ok.