Tiny white swimming things...

Okay so there is no chance for a picture. Every month or so, my tank becomes filled with little white creatures that look a lot like sperm. They are little white balls with a little tail and I can actually see them swimming. They aren't just being tossed around in the current. I can see them most easily at the surface of the water and usually they are trying to swim against the current.

I'm assuming it is one of my corals trying to reproduce, I have no anemones, and only a single shrimp.

The only other option I can think of is that I do have a mated pair of cardinal fish.

Thanks as always!!!

 

They could very well be fry from your cardinal fish.

 

A male Cardinal carries the fry in it's mouth until are they recognizable as cardinal fry or he eats them.

My other thoughts are shrimp larvae or epitokes of bristle worms.

 

"Plankton blooms" is what I've always heard it called. A lot of the benthic critters in your live sand produce free-swimming larvae. Once they mature, they crawl into the sandbed. That's why you see them in masses periodically and then they disappear.

 

I doubt it's cardinal fry for the reason Corailline mentioned.

Bristleworm epitokes seem like a reasonable answer, since I do have many.

Never heard of the "plankton bloom" but it makes perfect sense to me!

I guess the thing about this question is that the answer could be a number of different things and we might never really know.

Thanks again!

 

Do you have hermit crabs?

 

It's people like you guys that keep me sane....;D

Doratus, I saw some tiny things exactly like you describe swimming in a cave under my big rock. There were so many of them that it looked like a swarm of no-see-ums but also had a semen like look to them. I laughed but didn't dare have the nerve to post about it for fear they'd all think I was crazy. ;D Thank you for braving the turf and showing no fear.

 

Haha! Thanks, I was a little nervous, but then I thought: We're all friends here right?

 

I have one for sure.

If there is a second, (s)he is a master of concealment.

 

When I had that happen it was hermit crab babies. Could it be mysis shrimp?