Found this in my larvae tank...

Can anyone tell me what it is?

 

VIDEO: 

likely a hydroid
http://forums.saltwaterfi...389141/hydroid-problem

This was free swimming.

The medusa stage of hydroids are motile.
 
http://njscuba.net/zzz_bi..y/lifecycle_hydroid.jpg

Yikes, thank you very much for the info. The larvae have been in a bare bottom tank since 4/11 (5 days ago). Think it might have came with my brood stock water and I'm just now seeing it? Should I begin looking for more?

Yes, def. keep an eye out for more.  They are horrible for larval tanks given they can kill larvae. I bet it did come from your tank, they are one of the many dangers of using used tank water.

Ah, no good! Thank you very much for the help. Only three things have gone in my tank: brood stock water, RGcomplete, and Otohime TDO.
The larvae is now at 5 days. As soon as they get through metamorphosis I'll move them to the grow out tank.
Thank you again.

Oh sorry, I read it as you used tank water for the larval tank.
 
I have no idea how it got in there other than cross contamination.  I do not know if they can get airborne or not.
 

Broodstock water. 

Don't let fear and common sense stop you! =]

My pair live in a reef tank so broodstock water is tank water.  If I microwave sterilize tank water, will that kill the hydroids, or will that make the water less healthy/useful

I use new saltwater for my larvae.  I take it a step further and sterilize the new saltwater in the hatching/larval tank by adding 1 mL bleach per gallon.  I let that circulate for 12-24 hours, then dechlorinate with sodium thiosulphate about an hour before adding the eggs to hatch.  The eggs are "gently sterilized" by bathing in 5 mL hydrogen peroxide per liter for 15 minutes which seems to kill any hydroids that are attached to the egg tile.  I also scrub the tile everywhere that there aren't eggs.  Some people have poor success using this type of method, but I have decent success (about 98% 24 hour survival).  I am far from an expert though, so don't take this as advice, but rather an idea.  I stole the chlor/dechlor method from KathyL, I think I am doing it the same way she does. 

Don't let fear and common sense stop you! =]

Looks like some sort of jellyfish to me.  What is the diameter of that thing?  Looks to be about 3" across.

It is a hydroid medusae (as was stated above).  When I see them, they are typically less than 1/2" (12 mm) in diameter.  If you stand over a tank and say "Artemia" out loud three times in a row, they magically appear .

Heee.

check out Kathy's Clowns, llc website:
http://kathysclowns.com
Captive bred clownfish and more
(Wholesale to the trade.)

Heee.

check out Kathy's Clowns, llc website:
http://kathysclowns.com
Captive bred clownfish and more
(Wholesale to the trade.)

Artemia, Artemia .... no perhaps not, I allready have enough issues with them without tempting the wrath of Jim and his devil spawn

I have some things that are about an inch across that I thought were some kind of feather duster with a really short tube.  They act like featherdusters.  They have been in the same place, unchanged for months.  They aren't the sessile form of hydroid, are they?   I've never seen any thing that looks like branching.  They are really hard to photograph.

sounds like hydroids to me

Since taking this picture, I've found 2 more of these in my larval tank.

 
They are like rabbits.

Don't let fear and common sense stop you! =]

bleach the tank when you can.  They can become a real issue for you if you don't nip this in the bud.