Same here! I would have loved to keep a boxfish of some kind one day if they couldn't completely wipe out a tank if they freak out for some reason. I imagine in a very large tank constantly running activated carbon a boxfish could work but it sounds like a lot of effort. I think I'll stick with less toxic fish.That could be a reason...
Part of the reason I haven't considered one myself
I believe they get up to around 2 feet long also being built like a bulldog. I would not want to get a bite from one!
As far as I know, no species of pufferfish has more or less potent toxin than others, they all have the same toxin, tetrodotoxin, although I wouldn't be surprised if some species have higher concentrations of the toxin than others. You are correct, fugu is not one species, it can be any species from the genera Takifugu, Lagocephalus, Sphoeroides or Diodon (not really a pufferfish), but is usually from Takifugu, especially T. rubripes, the Tiger Puffer. It is true that all chefs that prepare fugu are highly trained to remove the dangerous parts (of which the liver and ovaries are the most dangerous), but mistakes do happen unfortunately, and there is no antidote for tetrodotoxin. There are some fugu farms that supposedly breed non-toxic pufferfish, since the fish themselves do not seem to produce tetrodotoxin, they accumulate it in their tissues from eating other animals that do, so by not feeding the fish any foods that contain it they do not have any of the toxin. There is some scepticism over this but it's definitely interesting.
They are usually only aggressive when breeding, otherwise they behave similarly to other triggerfish. I have seen a breeding pair in the wild while snorkelling, but I stayed well away (I was very wary of them) and they didn't bother me. I heard later that another person snorkelling in the area that day wasn't so lucky...
Oops, when I said 'behave similarly to other triggerfish' I meant ignoring people other than maybe a passing curiosity (or nipping, as you said).