Amos the puffer fish

Amos was a freshwater puffer fish, a member of the species Tetraodon mbu. Common names include 'giant freshwater puffer' and assorted combinations of the words mbu, giant, freshwater, congo and puffer.

Sadly, Amos died in November 2001. However, I'm leaving all the pages up, because he was an amazing fish! I haven't decided yet whether to get another mbu - they are the best pet fish I've come across, but I don't think another would ever replace Amos.

Most people know of marine puffer fish, and many fishkeepers know of brackish (half-and-half - generally found in estuaries where fresh and sea water mix) puffer fish. Relatively few people appear aware that there are also a number of true freshwater puffer fish. (A common cry from the dangerously little knowledge brigade - "one thing I know - all puffer fish are brackish or marine".) Amos was native to the middle reaches of the River Congo (which may be the Zaire, depending on current politics), in Africa. He was a true freshwater fish.

Tetraodon mbu - technical specs

There is relatively little published information on Tetraodon mbu. They appear not to be a species commonly kept as pets. The following is a combination of everything I have gleaned from various sources:

• Habitat The Congo River, Africa. Some people maintain it is native to other lakes and rivers in the area.
• Disposition Nasty, quarrelsome, violent and vicious. This does not describe Amos.
• Diet Meat, anything nice and solid. Snails and shellfish are a favourite, and the mouth comes with the teeth to deal with them.
• Sex No. There is no known way to identify the sex of an individual, and breeding has not been achieved in captivity.
• Water Conditions Temperature 24-26 deg C.
• Size Adults reach 75 cm (30"), and weigh 6.5 kg (14 lb). There are reports of specimens 100 cm long, but you know what fishermen are like...

Amos differed from the above notes mainly in that he is mostly peaceful - I have angel fish who are more aggressive. When I first got Amos he went into a community tank 'temporarily', with the warning from the fish-shop that he'd terrorise anything. He didn't, and he's always lived in community tanks since. Fish he has lived with (and should have bullied) include honey gouramis, tiny neons and rasboros, young angel fish, baby kribensis and more.

The problem is that those snail-crushing teeth are quite capable, and if he decides to attack, the target doesn't stand much chance. Once when he was small he took the head off a young kuhli loach but that seemed to be an abberation. Then, in July 1998, after two peaceful years, he decided a corydoras in the tank was a snack. Unfortunately, I witnessed this and it was not pleasant (corydoras are a small catfish - they have bony plates in/on the skin, and (I now know) are very crunchy).

So, Amos is basically peaceful, the angels bully him and plecos push him out of the way to get at his food, but I have to live with the realisation that if he gets peckish and fancies the look of anyone in the tank, he will kill and eat them very efficiently. I draw comfort from the fact that his diet (in the wild) seems to be bottom-dwelling shellfish, and (so far) he only seems to regard something as edible if it's lying on the bottom of the tank, preferably wriggling. Working on this principle, I think all his existing tank-mates are safe (the plecos are bigger than him - I don't think they look like snacks).

I may have a pacifist mbu puffer, but he is certainly no vegetarian.

Puffer fish crop up in one or two places on the web. This very short list has a bias towards more technical pages:

• Ian West has a page with quite a lot of information about puffer fish.

• The Medical Research Council are funding some research into puffer fish DNA. There's quite a bit here, including technical genome stuff I don't understand. Some nice pictures and also links to some other sites (including back here to Amos).

• John Friel was studying the functional morphology of feeding in tetraodontiform fishes at Florida State University. These pages include reports of puffer fish biting people and pictures of their teeth. (Amos bit me once, but he was small and it only hurt, I didn't lose any limbs).

• "It is 10 to 100 times as lethal as black widow spider venom ... and more than 10,000 times deadlier than cyanide". An illustrated article about tetrodotoxin, the poison in pufferfish (including T. mbu). Unusually for a toxin, it is not a protein.

• The US Food & Drug Administartion also have some things to say about tetrodotoxin, in the Bad Bug Book.

To comment on anything (please do) email ian.web@astounding.org.uk