Harlequin tusks are wrasses if I'm not mistaken(I really do not know much about them but I do know about fish breeding)and all wrasses are pelagic spawners meaning they disperse there eggs in the water column vs laying them on a rock or other surface(like clowns,gobies,dottybacks). Pelagic spawning fish produce very small eggs (about 1mm or less!)that are very prone to fungus and bacteria(especially vibrio sp)so even getting any/many hatchlings to work with is a large problem,second the larvae hatch out as prolarvae which do not have eyes,mouth,fins,gut,etc and keeping them alive long enough for the prolarvae to use up there yolk sack and grow a mouth,gut,eyes,etc is really hard because so many things can harm the prolarvae(ammonia and nitrite is usually the problem for hobbyist)then comes feeding the larvae , another huge problem finding food that's small enough ( 20-40 um possibly) and it also needs to be slow enough for the larvae to catch but fast enough to trigger a feeding response. I'm not really sure how to establish a breeding pair but with most marine fish you need to figure out which is the male and which is the female then figure out if they are like clownfish or most other wrasses and just getting to juvenile fish will get you a pair.