The genus Arothron contains fifteen species. A. diadematus reaches thirty centimeters whereas the largest, A. stellatus can get to an impressive 1.2 meters!
The fish is a Red Sea-only species and is related closely to A nigropunctatus, which has a distribution across the Pacific, though I think that the bolder markings of A. diadematus make it more attractive than its cousin. Both fish have the same way of swimming, as do the rest of the clan, using their enlarged anal and modified caudal for propulsion. It reminds me very much of an airship, though one that is capable of making very precise movements to graze on and around coral.
The fish lives alone except for a few weeks in summer when it gathers in shoals to spawn. It does seem to have quite an ‘interesting’ piece of behavior that I took to be a joke at first: according to a few sources on the web, the masked Puffer builds nests in the sand. Okay, this is normal for the family, but apparently they use their own sperm to reinforce the construction and masks their smell.
I’m not entirely convinced this isn’t a joke on Wikipedia that’s gone too far, so if it turns out it’s not true, then I think I’ll be relieved. Given this kind of behavior, would you want one in your tank?
The fish can store tetrodotoxin in some of its organs so please don’t eat one without consulting a fugu chef first. Also, the family (whose name means “four teeth”), apparently has the shortest known genome of any vertebrate. I’m not sure if you’ll ever need to know that, but just in case…