As for your question about keeping sharpnose.....it doesn't have a solid answer yet. A lot of places have tried to keep them without any luck yet. Things we've played with are tank size, shape, lighting, water chemistry, decoration etc...
We (there's more than a dozen places working on it) have seemingly eliminated various issues, but still have no luck. The best sharks have done well in the most basic set ups.....holding pools. Then when they hit the exhibits, they flip over dead.
In the past I kept some alive and going strong awhile. But when I turned over care to another aquarist, they died without reason. Last Summer I had two that I kept for several months in holding here at UWA. Eating strong, made it past deworming etc.... They made it less than a week on exhibit. Again, it's when care switched. We lost bonnets at the same time (which were raised in the same holding). It confused me. One thing I noticed on necropsy was that the person feeding them may have changed the diet. They seemed to do very well on squid. Howver, they don't pass the beak of the squid, so those needed to be removed. I found beaks in the stomachs. They were switched to a shrimp diet (peeled shrimp), and I think that combined with the stress of a quick move may have done something. In the wild, they seem to be highly specific eaters....going after mostly squid and crab (both bonnets and sharpnose). I think if we approached them as a similar species, and hammered out diet, it would be a big help. Also, sharpnose are stressed very easy. Like you said, they are a schooling shark. Many other fish I've worked with will stress to the point of death if not provided the correct environment. I think that is the real trick with them. They like open sandy bottoms. Most places have a course gravel substrate and some type of decor as an obstruction in the display.
