Parasites?

[Steve69]

I did a water change on my Oscar tank today and noticed something odd. I saw many long thin `crimped` green things which seemed to move....almost like worms and the same sort of thickness as plec poo. I`ve never ever seen this before and when I told my girlfriend she said she`d had the same things in her tropical setup and was told they`re a parasite

Any ideas what they are and how I can get rid (I managed to remove most via the gravel filter)?

Thanks.

 

[hamfist]

STart with something like Sterazin.