I've had the pair together for 7 months. I got the female in August and bought a smaller goby in september. Initially the female harassed the new addition for a couple of days. I thought I bought another female, because my larger goby wouldn't let the smaller one come out. Then four days later both were together sharing the same den. They were housed in a 12 gallon nano cube up until friday because the watchman gobies were picking on my clownfish. I had a 50 gallon set up with a pair of cap clowns, so I decided to move the gobies to the 50 gallon. The watchman gobies went into hiding and wouldn't come out to it. Today as I searched for them I found a white clump damgling from the rockwork. To my surprise they were eggs.