HELP! WORM ATK!

[C.Kok]

I think is caused by the frozen blood worms. I have this problem before.

 

[Gill Blue]

looks like a blackworm to me. at least whatever the LFS sells as blackworms. you're lucky. I've tried multiple times to get a population of these in my tanks.

 

[seedubs1]

I wouldn't worry about it.

Stir up your sand a bit when vac'ing detritus, and you should suck a decent amount of them out. And do some largish water changes.

Whatever you don't get, your fish probably will.