General marine isopod question.

[Atlanta Reef]

I'm developing a quarantine tank. I've been slowly adding bio media from the main tank to the qt tank. Recently, I've noticed some small critters, larger than copepods, that are populating the qt tank. I've attached a link to a Google photos video of the new isopods. Can anyone tell me if these are safe for the fish? I've read a bunch about parasitic isopods, but I haven't been able to find anything about how to tell the difference between the good and the bad ones. You have to wait until about 1/2 to 2/3 through the video before you get sharp focus.

https://photos.app.goo.gl/TSMz5PssGaisx7FR9
Also attached

 

[Sleeping Giant]

I'm developing a quarantine tank. I've been slowly adding bio media from the main tank to the qt tank. Recently, I've noticed some small critters, larger than copepods, that are populating the qt tank. I've attached a link to a Google photos video of the new isopods. Can anyone tell me if these are safe for the fish? I've read a bunch about parasitic isopods, but I haven't been able to find anything about how to tell the difference between the good and the bad ones. You have to wait until about 1/2 to 2/3 through the video before you get sharp focus.

https://photos.app.goo.gl/TSMz5PssGaisx7FR9
Also attached

you could attach them on the post

 

[Atlanta Reef]

you could attach them on the post

I thought I did. Here it is again.

 

[Atlanta Reef]

I thought I did. Here it is again.

It's kind of big. When I went to upload it the second time, the site told me it was still uploading the first one.

 

[ISpeakForTheSeas]

Can anyone tell me if these are safe for the fish?

The kind you have are known in the hobby as "Munnid" isopods, but name seems to be incorrect. It's likely they're from the same taxonomic superfamily, Janiroidea, but I can't say for sure at this point.

Anyway, these kinds are safe and could be considered beneficial for fish/a tank.

I haven't been able to find anything about how to tell the difference between the good and the bad ones.

It can be a bit tough depending on the kind of isopods (for example, differentiating between Sphaeromatid and Cirolanid isopods can be quite challenging), but generally speaking, the head (particularly the eyes), the tail, if they can curl into a ball or not, and sometimes the body shape can be used to tell if a pod is parasitic or not.

A more technical or specific breakdown can be accomplished using a good microscope, but it's not generally needed, and it's not easy/quick:
https://www.americanisopodsmyriapods.com/taxonomic-guide-to-isopods-of-north-america/isopoda

 

[Atlanta Reef]

The kind you have are known in the hobby as "Munnid" isopods, but name seems to be incorrect. It's likely they're from the same taxonomic superfamily, Janiroidea, but I can't say for sure at this point.

Anyway, these kinds are safe and could be considered beneficial for fish/a tank.

It can be a bit tough depending on the kind of isopods (for example, differentiating between Sphaeromatid and Cirolanid isopods can be quite challenging), but generally speaking, the head (particularly the eyes), the tail, if they can curl into a ball or not, and sometimes the body shape can be used to tell if a pod is parasitic or not.

A more technical or specific breakdown can be accomplished using a good microscope, but it's not generally needed, and it's not easy/quick:
https://www.americanisopodsmyriapods.com/taxonomic-guide-to-isopods-of-north-america/isopoda

Thank you! That's what I to wanted.