Ostracod or Acro White Bugs?

Nepenthes88 · Dec 15, 2020

Hi all!

I've recently had an explosion of these guys in my tank and I'm trying to determine if they have any correlation to a recent decline in several types of SPS (for perspective though my tank is relatively new so it may just not be time for SPS yet). I have a strong suspicion they're harmless Ostracods based on other threads but I still would appreciate an ID from someone with experience!

I've noticed these guys crawling all over recently dead SPS skeletons but I don't think I've ever noticed them on live tissue. They're also everywhere else...on the glass, on rocks, swimming around, etc. They move around pretty quickly.

Here's my best attempt at a video. The focus is a little off but you can see their movement pattern and their relative size. These guys are just on some live rock!

RedFrog211 · Dec 15, 2020

Unfortunately the video isn’t loading for me. If you can find a well focused frame and take a screenshot, I might be able to help identify

Nepenthes88 · Dec 15, 2020

Hmmmm strange the first video wasn't coming up for you. I just took another (better) video after lights out and put on YouTube. Hopefully this one work!

RedFrog211 · Dec 15, 2020

I won’t be able to give an ID without a microscopic view, but I’d say they seem really fixated on the algae and rock. You mentioned that you’ve only seen them on dead coral, so that’s definitely a good sign. It is still concerning that your SPS are suddenly dying off- I assume you’ve tested parameters? (Side note, love Nepenthes! Unfortunately, I don’t have a proper set up for the winter, so most have died off. Thankfully I have some sarracenia that’ll survive outside!)

Nepenthes88 · Dec 16, 2020

RedFrog211 said:
I won’t be able to give an ID without a microscopic view, but I’d say they seem really fixated on the algae and rock. You mentioned that you’ve only seen them on dead coral, so that’s definitely a good sign. It is still concerning that your SPS are suddenly dying off- I assume you’ve tested parameters? (Side note, love Nepenthes! Unfortunately, I don’t have a proper set up for the winter, so most have died off. Thankfully I have some sarracenia that’ll survive outside!)

Very cool about the Nepenthes! Not many people actually know what my username means. I actually have plans to someday build a greenhouse in the backyard for Nepenthes and orchids, just haven't made time for it with other hobbies!

I have tested parameters and everything is in check. I think the SPS die off may have been caused by temp fluctuation. This is a new 120 build and I underestimated how much winter temps would have an effect on my water temp so I didn't size my heaters correctly. It wasn't a huge fluctuation but nightly for about a month my tank would drop to 75 ish and come back up during the day to 78. However, while this was happening is also when I noticed the bugs so I'm trying to rule things out.

I do have a budget microscope so I'll try to get a decent pic. Appreciate all the help!

RedFrog211 · Dec 16, 2020

Unfortunately I don’t have too much experience with SPS. I just don’t have the resources or time to properly care for SPS. The heater may be the cause- I keep my tank at 78; but mines also a 20g.. haha that’s significantly easier to heat up. Were they thriving before the sudden decline?

maxberter · Tuesday at 6:50 PM

I'm not sure you will see this, but I have some little critters that look exactly like this wondering if you ever definitively figured out what they were?

Nepenthes88 · Tuesday at 7:41 PM

maxberter said:
I'm not sure you will see this, but I have some little critters that look exactly like this wondering if you ever definitively figured out what they were?

Hey there!

I never got a definitive answer to what they were but they ended up disappearing. The main thing I suspect contributed to them disappearing was adding fish that likely ate them such as a sixline wrasse and multiple types of damsels.

At the end of the day, I don't think they ever contributed to killing anything...they just seemed concerning at the time because I wanted to make sure I didn't have one of the commonly discussed "bugs" that kill SPS.

maxberter · Tuesday at 9:21 PM

Nepenthes88 said:
Hey there!

I never got a definitive answer to what they were but they ended up disappearing. The main thing I suspect contributed to them disappearing was adding fish that likely ate them such as a sixline wrasse and multiple types of damsels.

At the end of the day, I don't think they ever contributed to killing anything...they just seemed concerning at the time because I wanted to make sure I didn't have one of the commonly discussed "bugs" that kill SPS.

Wow thanks for the quick response! Mine look exactly the same as yours. I plan to use a microscope tomorrow to look at them and will let you know if I have any luck. I have a FOWLR tank, so not that concerned.