White small organisms found near water surface

[Edwin]

Hi.

Urgent question. Found a lot of these white little things on the water surface of my opae ula tank. They wiggle about and can be found on the walls as well. Majority though are at the surface.

I hope they are larvae but for the past few days I have been staring but I do not remember seeing any berried shrimps. I did a water change 2 days ago by adding in brackish water mixed using distilled water and reef salt. I added in the new water to fill tank to brim and scooped out after to return water level to its original level. I was not home yesterday and I found these out today.

Are these larvae? If not, what are they? Should I scoop them out? Are they harmful?

Thanks for the help!

[tooth]

Hello Edwin,
The image is a little fuzzy on my monitor, but they do not appear to be shrimp larvae. Larvae don't wiggle, they mainly rise and fall slowly in the water column. They do, however, tend to rise to the top when the light is on--they are positive phototropic. And, they are red-ish with a very noticeable large (compared to the abdomen) red head, nearly as big as the egg itself was.
I can't tell what they are for sure on my monitor--copepods maybe? I don't know enough about copepods to say if they are a threat to shrimp, but I'd remove them just the same.
Regards,
Brad

[KenCotigirl]

My guess is copepods. Harmless. Would ignore them. Their population seems to ebb and flow over time. The larvae seem attracted to light. The larger adults will often be seen carrying eggs.

Ken

[Jackal148]

Do you have any other critters in the tank besides the shrimp? They look like hermit crab larva. I have a few Blue Leg Hermits in my 6 gallon Fluval with my shrimp and at one point found larvae as you describe in my tank every two weeks or so. "Wiggled" around for two days or so and then would disappear (probably died) until a new batch showed up. Was able to see the crabs mating? At least that is what I think it was. Two crabs would get side by side, one would leave its shell and go into the neighbor's shell. A short while later, it would come out and get back into its own shell and both would go off on there own. Seems that it was always the smaller one getting into the larger one's house. Entertaining to watch.

[Edwin]

Thanks all for replying. Image is fuzzy as I had to enlarge them when taking photos in order to see them at all. No other animals in there so don't think it's the hermit. Hmm... guess I will leave it in for the meantime as I do not want to unnecessarily disturb the shrimps at all. Unless it is identified to be harmful. I hope not