125:72X18X22. 150: 72X18X28. 180:72X24X24. I am just stating the obvious. Going by your logic, i'd be no different with a 125 or 150. Or even a 75 with the same footprint. Would a shark be happier in a 180 or in the ocean. I learned from my mistake and I think no one else here does. Sharks belong in the ocean or a public aquarium. Regardless. Does 6 inches of width really make that much of a difference? When the average person buys a shark egg, baby, whatever. They are excited, wow, I got a 180 gallon and a cool shark. Then a year later, "i'm bored, this thing just sits there, and I just keep feeding him, and he keeps geting bigger. I wasted all this money on the tank for this?" Then the 24" shark ends up in a 30 gallon holding tank at an lfs where it mystriously dies. Then the owner says, gosh, now what am i going to do with this huge tank I was told to get? It's too big to cost effectively make it into a reef way too big to stock with pricey marine fish. Damn, I should have gone with the 75 gallon i was going to get and was talked out of. Mind you, this isn't always the case, but it is the norm. I guarantee you.