ID for new critters in tank

[captexas]

The other night I decided to break out the flashlight and check on the tank since I hadn't done it in awhile. In one corner I have a large clump of feather culerpa that seems to have become a haven for pods and other little creatures. One type that I hadn't scene before look almost like tiny little shrimp. The largest one I have scene is may 5/16in. and most are smaller. They are mostly clear in color and look to have a split fan tail like a shrimp with two little eyeballs at the front as well. They swim around and change directions rapidly and it is hard to get a good look at one as they really don't stop and perch anywhere. They are also mostly active at night.

Anyone know what these are? If they are shrimp, how did they get in my tank all the sudden?

[Gin_Tseng]

This same thing happened to me too. I;m guess that there were some eggs in your live rock. At first I just saw about two or three of them but now there are a least 30 of them in my tank just swiming around the bottom and I still don;t know what they are.

[MikeP]

Both my cleaner shrimp and peppermints spawn pretty regular - the larvae rarely last more than a few hours though. It's possible it's a larval shrimp more likely it's a mysid. The point where larval shrimp metamorphose to what you are describing is a few weeks and I doubt they were able to find food - when they spawn you know it - they are everywhere.

When I first got my fire shrimp second night in tank I got home late from work and it was releasing larvae - too bad I couldn't raise those suckers they are not cheap.

Also are you sure they are not some kind of isopod (could be pretty bad - ask Josh I think he had them) or amphipod? Try dropping some shrimp or clam meat in a spot then waiting and hitting it withthe light to see if you can get a good look at them.

[Troy Valentine]

Chris-

Sounds like you've got mysid shrimp in your tank. They are mainly phytoplankton feeders. And they are a great supply of food for your tank.

[DeletedAccount]

Sounds like the little guys I have in my overflow living in the weeds! I take the macro out and "rinse it" into the main every once in a while and everyone goes CRAZY! It's a wonderful feast for the fish and shrimp! The ones that I have do not grow large, maybe 1/4 IF you could stretch them out.

[witecap4u]

hope this isnt what you have.....Cirolanid Isopods

http://www.reefs.org/hhfaq/pages/picture_pages/faq_cirolanid.html

[captexas]

Witecap -
No, those aren't what I have, but thanks for the link as the pics helped identify what they are. Definately mysid shrimp. My new question is how did they get there? My tank has been up for 8months now and I just now found them. I guess some larvae could have hitchhiked in with a new coral or something. Kinda cool actually. Hopefully they can keep reproducing in their feather culerpa hideout.

[::pete::]

Ok the link to the cirolanid isoprods got me nervous after seeing a little critter running (swimming) hard to tell, thru my zoanthid. So I grabbed some water from the tank and put it in an empty tank as to isolate. I shook the rock a bit holding it upside down to see if what I saw would fall. I got several what look to be mysid shrimp and am hoping that, what was crawling (swimming) was just a little shrimp (not completely formed). They are of different size and one has a large belly almost greenish in color. The link to the cirolanid isoprods shows a "BLACK EYED" critter. Although the critter in my tank has eyes they are not as pronounced, heck almost as invisible as the critter. Any help or comfort would be appreciated.
Thanks Pete

[::pete::]

http://www.calacademy.org/research/izg/SFBay2K/mysid_shrimp.htm

The above link is definitely what is swimming in the little tank.

[::pete::]

any response

[Chris]

http://www.calacademy.org/research/izg/SFBay2K/mysid_shrimp.htm

The above link is definitely what is swimming in the little tank.

Definately a good thing for your tank. Don't worry about it. ;)