Need help identifying mysterious yellowish orangish nudibranch

[19Mateo83]

This little guy came off a Platygyra frag today. Does anyone have any idea if it is good or bad? @ISpeakForTheSeas

 

[ISpeakForTheSeas]

I'd say an Elysia species:

Elysia flava or E. obtusa - harmless/beneficial Sacoglossan slugs. They're herbivores, with E. obtusa known to feed on Bryopsis, while E. Flava is thought to feed on Cladophora. As mentioned below, I don't know if these are required feeds or just strongly preferred feeds:

Some lettuce slugs (typically from the genus Elysia) will eat nuisance algae species, but their wild diet varies pretty drastically from one species to another, and some species have some pretty specific wild diets (I don’t know if these are required diets or preferred diets, but Reef Cleaners reports that they'll eat just about any green, fleshy algae). That said, Elysia slugs generally feed on siphonalean algae such as Caulerpa, Codium, Acetabularia, Halimeda, Udotea, Byropsis, and Valonia spp. So, in theory, these guys should eat nuisance algae that pops up in your tank.

 

[19Mateo83]

I'd say an Elysia species:

So it’s safe to add as part of my CUC?

 

[Uncle99]

Yes, that species, but it will likely starve.

 

[Tired]

Likely to starve, but yes, a slug that exclusively eats seaweed and/or algae is reef-safe.