Strange Filterfeedin Worm Culture

[AQUANUTS]

ive got a new tank setup over tenweeks which ive moved my redtail cat and 3 pangasus an 2 arrowanans in to and have a strange culture of filter feedin worm like creatures growin they are at the end where the inlet is from my 5 external filters are i dont feed live food only feed pellets and trout for the redtail and arrowanas and waterqualitys are very good ph 7.1 nitrates nil ammoniea nil phoshpate very low carbonate hardnes is only 4 so im stumped any ideas or it looks like me byein a microscope and lookin at it any help as it is growin day by day

 

[thegnu]

if they are filter feeding, by that i guess you mean they have like very small arms or branches and are waving about then they are hydra. they pose no danger to adult fish but can be fatal to small fry. they normally come about when a tank is over fed and has a dirty substrate and a high aerobic bacteria count, a bit like when planeria turn up when feeding infusoria to fry

 

[BigC]

If you are sure then use Flubendozole 5% powder to totally eradicate the Hydra. totally safe in the correct dosage. I breed Killifish and I have had to dose for Hydra quite a few times on different occaisions in fry tanks where I am feeding up to 4 times daily.
http/en.wikipedia.org/wiki/Hydra_%28genus%29

 

[AQUANUTS]

ok thanks for the help just added a uv on to one of me external and changed me substate from silver sand to fine gravel me red tail a bit chessed of with the change but its lookin clear of them if it happens again ill use treatment just dont like usein chemical again thanks for your help