Critter ID please

[JBAqua]

I am new to CanReef and new to s/w and have a question. My tank hs just been set up for 1 month. I spotted this unknown critter in my tank. :confused: (I think it must have come with my live rock).

Someone mentioned to me that it might be some kind of nudibranch. Is it? If so, what kind is ir and is it a problem or just a neat creature to have in my tank?

Sorry for the picture quality (I'm no good at closeups of tiny creautures :redface:. The creature is black and just under 1/2 inch long.

http://www.canadianaquariumconnection.com/jb_images/unknown1.jpg

I'd appreciate any insight you can provide. Thanks.

[ScubaSteve]

Definitely a nudibranch. Without a better pic I can't really say what kind. Nudibranchs are obligate eaters (only eat one thing), so unless you have that particular food in your tank it likely won't survive. And if its prefered food IS in your tank, you probably don't want him eating it because you probably paid good money for it. It's a bummer, nudibranchs are my favorite sea critter but they're damn near impossible to keep.

Can you snap a better pic and give me an approximate size? I'll see if I can figure out exactly what it is.

[JBAqua]

Thanks so much for the prompt reply. It looks like a really cool creature. Too bad they eat only one thing. But I guess if it's something expensive that they eat, I won't want them doing that. As this is a new tank, I don't have anything in there so far except 3 mollies, 2 hermit crabs, 1 nassarius snail and 3 adult cerith snails (and baby cerith snails), so nothing's at risk at the moment... nor will there be food for it, I guess.

I snapped that photo last night when I spotted the nudibranch. I'll try to get a clearer picture to post next time I see it.

Size: 1.2 cm long x 0.2 cm wide (approx.)