Sadly, Caspar died after only a couple of years in captivity. I'm not sure what killed him, but the symptoms were very like a stroke: one day he just stopped eating and swimming, he lay on the bottom of the tank and occasionally wiggled with swimming-like movements, but didn't actually move forward. Most worryingly, his eyes didn't follow movement in the tank, even of bits of food. He got thinner and thinner, and died. This page remains in memoriam...
Caspar, like Amos is a freshwater puffer fish. Caspar is a Tetraodon miurus ('Tetraodon' - derived from something to do with four teeth - is the genus to which most freshwater and brackish puffer fish belong). Caspar' species doesn't have much in the way of english common names, but is sometimes called a 'congo puffer', even though that can lead to confusion with T. mbu - Amos' species.
There is as little published information on Tetraodon miurus as on mbu. Neither appear to be a species commonly kept as pets. The following is a combination of everything I have gleaned from various sources:
Caspar matches the published descriptions almost exactly. One thing I've not seen in any published description, but which every owner I've corresponded with reports, is a very variable colouration - everything from very dark brown to a pale orange can be seen on the same fish in different moods.
Oh yes - and he buries himself in the sand of his tank, so only the eyes and mouth protrude.
To comment on anything (please do) email ian.web@astounding.org.uk