So i just got another yellow watchman goby, hes smaller than the one i already had in the existing tank. i saw the goby already in the tank go into the gobies "house" that the new one was in, and i havent seen the new goby yet. Should I be worried that the old goby killed the other one? I wanted to get a mated pair but has anybody had problems with two YWG's not getting along with each other?