About a year back, someone gave me a ozen or so green lettuce nudibranchs, which i added to the tanks containing by G. platysoma, G. ternatensis and G. viridis. they started to disappear (No bodies) within a week or so.
Aren't they pretty much just snails without shells?
I am not sure if they were eaten, but there was plenty of food for them (They ate heartily on my grape caulerpa, as well as algae.
-Ron