‘Why don’t you go into Angel Aquatics and get some more angel fish?’ said Mrs Gee, thinking that our very large (136-litre) tank was down to just two fish – one Plecostoma, and one large angel fish, so was looking rather bare. I needed no encouragement and soon found myself in the Fish Room but there were rather few angel fish, all rather small. Perhaps small enough to be snaffled by the Plecostoma, which goes round the tank like a Roomba, snarling up anything small enough to fit into its mouth. But then I saw this:
This. Recently.
This is a Senegal bichir (Polypterus senegalus), a freshwater fish from western and central Africa, and I fell in love. Why? Because, as a palaeontologist (recovering), I appreciate extant signs of a lost world. The bichir is a member of an ancient lineage (it includes sturgeons and paddlefish) that extends right back to the Palaeozoic Era. Like all fish once did, it has functional lungs (in most fish this has since evolved into a swim bladder) and the pectoral fins are like stumpy little legs. Bichirs can even survive and move around quite well out of water. Mrs Gee, on being told this, wondered if Steve (it is called Steve) might make a break for freedom and will be seen scuttling down the garden path to the pond.
Here is Steve from the front, showing a rather smiley face like an axolotl (we used to keep axolotls a long time ago, they are now exolotls), and the resemblance is not a coincidence. All fish once had faces like this, before the highly evolved jaw mechanisms found in more recent fish — the teleosts, a group that evolved much later and which mow includes virtually all fish you can name, from swordfish to seahorses, from trout to turbot). Tetrapods – a group of fish that came ashore, have faces rather like this, though this does not reflect close relationship, more that tetrapods have retained the ancestral fishy face that most extant fish have now lost.
Steve. Front view.
Despite its seemingly happy demeanour, a bichir is a fierce predator and would soon denude a tank of all other fish unless I gave it, as protection money, a fresh (defrosted) mussel each day. At the same time I bought three golden cichlid-like fish as its backing group. They all came from the same community tank as Steve, so I hope it’s learned more peaceable ways than its fellows in the wilds.
UPDATE: Sadly, Steve started to nibble at the other fish so I had to take him back to the shop. I got three more cheerful cichlids instead.
