After few jumps did it crossed your mind that sand in a nano does not sustain his requirement for food in the sand?Gobies are great for sifting sand, but if you have a certain sand scape in mind the goby will definitely change it, sometimes they will try to cover corals with sand as well, and they are known for jumping, take it from someone who knows, I have gone through (no exaggeration) at least 35-40 gobies in my reefing history and most were from jumping and the others have been from going into an anemone just out of pure curiosity, it got so bad that the local fish store owner felt so bad for me that he would give me free ones for a while, just to see how long they lasted, this was also with a mesh cover on the tank but since it was a nano with a rounded front couldn't get it completely covered, but they always found a way out, my opinion not the smartest fish. But what a sifter!