I have a diamond goby in my 125. I havent had him a month yet but i have always kept open top tanks and so far this one hasnt jumped at all. Fingers crossed. I love him my sand bed is always immaculate. I have also had a barred dartfish or chinese barred goby and he was in my open top 55 for 7 months before being transferred to the also open top 125. Never jumped one time. Not saying they dont or wont jump because ive heard enough horror stories to know they can and will. Just wanted to share my experiences to date. Tho i really cant imagine the diamond goby ever jumping out he never strays more than a few inches above my sandbed. And the only time he comes off the sandbed is to perform a cery odd "daily cleansing" as ive labled it. After hes spent a few straight hours sifting sand through his gills he swims to the center of the tank where the flow from my two biggest powerheads intersect at the top of the water, and the flow is forced downward pretty strongly and so he will invert himself straight up and down directly into the oncoming downward flow and open his mouth and gills as wide as possible and just kinda hover there like that for a minute or two just a few inches off the sandbed like hes trying to let the current blow his mouth and gills clean! Its the most unbelievable thing ive seen in my entire two years of reefing. I plan on trying to video next time im around to see it. Anyway didnt mean to go off topic but was compelled to share that story. Good luck with your goby hope he never venture out to the carpet!!