I wouldn't be surprised if some national/city/state aquariums do have reproduction from fishes ordinarily beyond our means to reproduce...but even for these huge tanks one problem is that our water circulation kills the eggs and hatch. If we could get a circulation system that could work on a kind of two-tank 'surge' and yet not suck the eggs into a filter, who knows? Maybe using gravity and a motive force to lift could create a no-kill surge. We already have a filterless filter, in live rock and sand.