what is this? Microscope picture included

[saltybagel]

So my tank has been battling some cyano and brown algae (dinos?) for a little while now when I accidentally let the nitrates/phosphates bottom out, and along with that I have been seeing a lot of white moving dots all over the glass.

I took one of them out and it looked like below:

I also took out a clump of the greenish brown algae and saw a bunch of smaller ones... They look like little underwater ticks.... these can't be copepods, can they? I've seeded my tank in the past with Ecopods, but these don't look like anything on a common ID thread. I'm worried these are bad news. Any help IDing these would be really appreciated!

 

[DaJMasta]

Looks like an ostracod to me. Big category of small crustaceans, I think likely most are benign. Do you notice the things they're on being irritated?

 

[saltybagel]

Looks like an ostracod to me. Big category of small crustaceans, I think likely most are benign. Do you notice the things they're on being irritated?

Thank you for the ID!! After a quick google search they definitely move around like an ostracod under the microscope. My tank only has red macroalgae, kenya trees, photosynthetic gorgonians, and a hammer coral. While the hammer coral is a bit retracted nowadays, I haven't seen any actually on top of any corals and I am suspecting that has more to do with the water chemistry still getting back to stable parameters. I've only ever seen the large ones on the glass and on hair algae/dino clusters.

Do you know if ostracods are known to eat live corals at all? Is that something to look out for?

 

[DoktorZhivago]

eat

Ostracods are filter feeders and detritivores. Lots of times people call them seed shrimp in fresh water aquaria. They're not as well known as copepods and amphipods but they're probably equally abundant in most aquatic environments. Completely harmless part of the biome of your tank and a food for larger filter feeders like corals. Some of the big ones might even be snacks for fish