Good or bad nudibranch?

BAMslam93 · Saturday at 10:08 PM

Hi all,

I recently came back from my LFS to pick up some corals and I thought I got lucky enough to get a berghia nudibranch hitchhiker on my acan but I'm not sure if it's a good nudi or a bad one like a zoa or montipora eating nudibranch.

Tahoe61 · Saturday at 11:33 PM

Well I would isolate it until you get an ID.

BAMslam93 · 2026-09-06T03:07:38-0400

Tahoe61 said:
Well I would isolate it until you get an ID.

Yup, I have it in a measuring cup and trying to keep it aerated with a pipette. So fascinating!

BAMslam93 · 2026-09-06T22:02:06-0400

PolypPocket · 2026-09-06T22:50:48-0400

How cool! But it doesn’t look like a Berghia, at least not the color.

Following to see who can ID

Edit: I take it back, after looking at photos it could be. I guess ignore what I said lol

Baldyreef · 2026-09-06T22:56:21-0400

20260906_195615_8576EFFC-21EA-4037-8704-243238C9B7F1.png

Could this be it?

BAMslam93 · 2026-09-07T14:58:09-0400

Baldyreef said:
Could this be it?

Possibly? At least it's body looks similar. I don't have an aiptasia problem anymore so I wouldn't want it starving in my tank but I don't want to risk my corals either

troublemaker · 2026-09-07T15:21:52-0400

A full Bertha will darken substantially, the white ones you see are hungry. I’m not IDing what you have, only letting you know that Bertha are not always white.

PolypPocket · 2026-09-07T16:01:36-0400

troublemaker said:
A full Bertha will darken substantially, the white ones you see are hungry. I’m not IDing what you have, only letting you know that Bertha are not always white.

The Berghia nudis get darker?

EnterName · 2026-09-07T17:12:45-0400

PolypPocket said:
The Berghia nudis get darker?

Yes, when they feed on (Ex)Aiptasia they store some of the tissue in their cerata (it's part of their digestive system). While Berghia uses the cnidocytes of the eaten (Ex)Aiptasia to defend against predators other Nudibranchs extract chloroplasts or symbionts and then profit from the photosynthesis these cells are capable of... fascinating creatures.

Unfortunately that makes the identification a bit more difficult from images... There are MANY white nudibranchs that have these long cerata (many Aoelids look that way), that's why I'm not feeling comfortable giving an ID here. The images are very blurry and there are just so many that look similar...

PolypPocket · 2026-09-07T17:17:24-0400

EnterName said:
Yes, when they feed on (Ex)Aiptasia they store some of the tissue in their cerata (it's part of their digestive system). While Berghia uses the cnidocytes of the eaten (Ex)Aiptasia to defend against predators other Nudibranchs extract chloroplasts or symbionts and then profit from the photosynthesis these cells are capable of... fascinating creatures.

Unfortunately that makes the identification a bit more difficult from images... There are MANY white nudibranchs that have these long cerata (many Aoelids look that way), that's why I'm not feeling comfortable giving an ID here. The images are very blurry and there are just so many that look similar...

That’s really interesting! And makes sense being other Nudibranchs like the lettuce one gets its color from food (like you mentioned).

BAMslam93 · 2026-09-07T17:44:27-0400

Sorry my phone is a potato lol. Maybe these help?

PolypPocket · 2026-09-07T19:59:32-0400

BAMslam93 said:
Sorry my phone is a potato lol. Maybe these help?

You could always test it if you have any Aiptasia. If it eats one then you know

#re#reefsquad

Fish Fan · 2026-09-07T20:25:15-0400

I don't know, I'm certainly not an ID expert, but I've been shopping for Aptasia Eating Nudibranchs all day, and what I see here doesn't quite look like one of those to me

I don't know if @ISpeakForTheSeas or @thamnasteroid would have a minute to take a look, but it would be great if they could