So hopefully this is related enough to put in this thread. I've always wanted to keep sharks, but have put it off while I'm renting as the wife and I are looking for a house. We're looking hard at something right now and if we wound up with it I would excavate and add on, right now we're looking at a "tank" of 20'x10' with a depth of 8'. Of course I'd round out the corners and scape it so that swimming channels would actually be somewhat circular.
Logistics of the actual build aside, what sharks, if any, would be comfortable in something this size? I know it's an ambitious project but for us it's actually do-able. As long as it isn't built yet, should I consider making it larger? The viewing area will be two 8' wide panels, hence the 20' side. So really the only dimension that could fluctuate would be the 10' side, but probably not by much. We're somewhat limited in that we'd be building this on the south side of a house so that we get use of natural lighting (supplemented, of course).