Still sound like tubifex, 4-5 3" corys will eat most of them in a week, they will end up looking like marbles with fins. Most fish won't bother corys.
You will also need to siphon your substrate. I'd leave them but I add them on purpose.craig said:I had the same problem a little while back. Do a 50%water change.Then do a 25%water change every other day for three days. And feed your fish very sparingly during this time.The worms will die.
Do you mean removing the gravel first? If you do then washing the gravel in clean, very hot water works just as well.dialphantom said:bleach will do the trick