Help with ID

rabid_1 · 2026-09-03T17:24:11-0400

Hi all, was hoping for some help from the experts! I have thousands and thousands of these guys on my glass now, they don’t look to be copepods which I have dosed, possibly ostracods but just want to confirm as there is so many of them now! Thanks in advance!

Tahoe61 · 2026-09-04T07:48:05-0400

Looks like they are likely Ostracods, you can really see the little shell like body. I wonder if they came in off the pods you added. At least they are harmless.

EnterName · 2026-09-04T08:06:51-0400

While I'm not 100% sure, I would also say these are Ostracods of some sort. There is a wide variety from very small ones to quite "large" ones that can be seen with the naked eye without issues.

If you take a closer look they should basically look like a bivalve but instead of a mollusk they house a crustacean.

I'm not aware of any harmful Ostracods in reef tanks so even if you see them on corals chances are they are not a cause of harm and rather eat already dead tissue or so. The only negative effect they could have is the reduction of your copepod population if you have a predatory species.

Edit: There are parasitic Ostracods but no verified reports of them causing issues in reef tanks as far as I know. They would probably be smaller as they need to fit in fish gills properly

rabid_1 · 2026-09-04T16:15:59-0400

EnterName said:
While I'm not 100% sure, I would also say these are Ostracods of some sort. There is a wide variety from very small ones to quite "large" ones that can be seen with the naked eye without issues.

If you take a closer look they should basically look like a bivalve but instead of a mollusk they house a crustacean.

I'm not aware of any harmful Ostracods in reef tanks so even if you see them on corals chances are they are not a cause of harm and rather eat already dead tissue or so. The only negative effect they could have is the reduction of your copepod population if you have a predatory species.

Edit: There are parasitic Ostracods but no verified reports of them causing issues in reef tanks as far as I know. They would probably be smaller as they need to fit in fish gills properly

Thank you :)