Any idea what these are?

[Marcom12]

This is growing on the underside of a rock. The aquarium is new maybe 2 months old. No fish yet just a very small clean up crew. Any ideas what they are?

 

[Oscaror]

This is growing on the underside of a rock. The aquarium is new maybe 2 months old. No fish yet just a very small clean up crew. Any ideas what they are?

Hydroids, usually clear out over time

 

[Marcom12]

Nuisance or beneficial?

 

[Oscaror]

Nuisance or beneficial?

Nuisance

 

[Marcom12]

Ok so, just don't let it spread much? I don't add any food really...

 

[Oscaror]

Ok so, just don't let it spread much? I don't add any food really...

Cutting down on feeding helps, best way to deal with them is just by manually removing them

 

[Marcom12]

Ok thank you