have you noticed any damage to anything in the tank? it may be a good idea to get him out as he could start eating things. do you have anywhere to put him like a sump? you could leave him in and see how things go on but it may be difficult to get him back once he's in.
There's no damage in the tank but I'v not seen him since. Only got a brief glimpse of him. Don't want to dismantle all my rockwork if he may be a good guy. As for the photo - I think he's camera shy...