Need help identifying new tank inhabitant...


Lifetime Charter Member
Lifetime Member
Apr 3, 2005
just outside of Ottawa, Ontario
Hi folks,

I've got a 125g marine tank containing only macro algae, of Chondrus, Chaetamorpha, Ulva, and a dying Fucoid. Recently, I've been dealing with a brown diatom issue, which seems to be clearing up.

Upon close inspection of my tank, I've noticed some new 'inhabitants'... They are extremely fine, filamentous organisms that look like some kind of 'branch algae'. I've tried Googling 'branch' and 'algae' but nothing looks similar. I've tried to photograph it, but they are only about 5mm long, and don't really show up in my shots. They grow off of my Chondrus crispus (which lead me to believe it was part of that algae..), and also off of some of my filter's plumbing.

The best way I can describe it, is as a tree branch with no foliage - only much smaller (so far 4-5mm is my longest one).

Any clues on what I might Google to try to identify these?

If it helps, it's a coldwater tank, all other specimens in this tank were harvested off of the Maine coast..