Beautiful fish!!! I also have a Harlequin Tusk....and YES they do jump. I noticed mine was missing...sort of forgot as it was busy around here....
and a couple weeks later after we had searched the floor, sump etc...we decided to check the overflow...low and behold one HT fish!!!! A bit battered up as the overflows aren't very large...but after a few days of swimming and regular feeding he is back to his normal self..and once again the tank is covered with eggcrate.....