Hi,
You can catch the goby, I had to catch mine after watching it eat all the polyps off my acros- many of which did rtn shortly after. I gave my fish to a guy here in Oly with a softie tank, if you are in the Puget Sound area he will give yours a good home too. They can't help it, they clear a bit of acro to lay their eggs on. I think captivity makes them alter their behavior. They perhaps expect the offspring but don't have a mate so keep clearing and clearing in hopes of attracting one. Just my speculation. Green clown gobies single or not never gave me this trouble, just the one single yellow one. Maybe it's the yellows plus being a single fish.
If you have a large tank and a coral or cave it really likes try slowly lifting the coral with the fish in it slowly with a net under it til the net is mostly around and under the coral. Lift the coral out and hopefully the fish will let go. Or if the fish doesn't hide in a specific coral or rock have a friend tease it into a corner where you have the net below the fish, raise the net up real fast under it. That's how I got mine out. Took half an hour but it was worth it. Only broke off 5 digitata frags which I glued to a rock and sold to an LFS for 20 bucks. I'm happy! And my friend loves his free fish.
Kate