Tuxedo Urchin lost spines

[IL613]

I recently downsized my 20G reef tank into a 10G, and every animal and coral seems to be thriving except for my tuxedo Urchin. He's acting normal, tentacles extended, but one small section of spines appears to be missing.

My guesses are (1) that he's stressed and (2) that my halloween or one of my dwarf red-legged hermit crabs picked on him. Thoughts?

 

[fishguy242]

hi,any pics ?

 

[Spieg]

2 urchins in a 10 gallon? It's going to be difficult to keep them both fed.

 

[Jekyl]

2 urchins in a 10 gallon? It's going to be difficult to keep them both fed.

+1 tank is too small.

 

[r20crazy]

its probably starving to death. get some nori sheets and put some under a rock or frag plug (to hold it down) somewhere they can reach. or set the urchin directly on top of some until you can find a better/bigger home for it

(I'm in LA and could use it.... I have a major algae issue in my 40g. PM me if interested in rehoming)