The humble gourzon-a fish in trouble water |27 September 2004
There, holding a large mug of hot tea and perhaps a galet smeared with home-made karanbol jam, I sit in front of my mother’s freshwater aquarium. If I’m lucky, the prawn or kanmaron, a bundle of translucent intricacy, will not yet have retired to its hole under the stones in one corner, and the bigorno delo dou, a loveable shiny black snail, will still be crawling across one of the sides just before it, too, goes into hiding. But now that it is daytime, it is the fish known as the gourzon that steal the show.
Used to being fed at around this time, they press their heads expectantly against the glass, turning this way and that in a frenzy of fins and tails. The males are more colourful, with seven rows of red spots laid out on a pale olive brown background on each side of the body, with more red dots sprinkled all over their fins. The females lack the pretty red spots but have one or two black patches on the dorsal or back fin. In both sexes there is an iridescent blue glint below the eyes. All in all, quite an attractive fish.
I thought a lot about the gourzon in October last year when a team of biologists from the Association Réunionnaise pour le développement de l’aquaculture (ARDA), the Muséum national d’histoire naturelle in Paris and the Seychellois Ministry of Environment and Natural Ressources discovered a new species of freshwater fish on Mahé. I was glad that this would draw attention to our native freshwater fish, including the gourzon, which most people do not seem to realise is one of our precious endemic species – found nowhere else in the world.
It was during the second half of the 19th century that scientists first became aware of the existence of the gourzon. In 1866, the German-born curator of the Zoological Department of the British Museum (now the Natural History Museum) in London, Albert Günther, who had a penchant for ichthyology (the study of fishes), published volume 5 of his monumental Catalogue of the fishes in the British Museum.
On page 314 there was the description of what he called Haplochilus playfairi - Haplochilus meaning “simple lip” in Greek, and playfairi derived from the surname of Lieutenant-Colonel (later Sir) Robert Lambert Playfair, the British Political Agent in Zanzibar from 1862 to 1867. The specimens that Günther based his description on had been collected in 1864 and 1865, but I have not yet been able to find out what role, if any, Playfair played in this. What we know for sure is that the two men were good friends and Playfair sent Günther many specimens of fishes he collected while in Zanzibar – indeed they even co-authored an ichthyological masterpiece, The Fishes of Zanzibar.
In 1867 the gourzon attracted attention again when Edward Percival Wright, Lecturer in Zoology at Trinity College in Dublin (Ireland), better known for discovering the bwa sitron on Ile Aride, tried to carry live specimens back to Europe. When Wright left Mahé on the 23rd of November on board the Erymanthe, his luggage included a water jug with seven gourzon that he had caught in a stream at Mont Fleuri. One fish jumped out very early during the trip but the others reached Suez still alive, Wright having to catch flies with which to feed them. In Alexandria (Egypt) there was a major setback. Wright, who was now travelling by train, later recounted: “Here I placed them for a couple of days in a glass vase of Nile-canal water; but whether from its coldness or from its being so full of mud I know not, in one night two died.” Incredibly, in spite of a cold and stormy sea passage from Alexandria to Marseilles (France), the four remaining fish were still alive as Wright set off for Paris by train. But by the time he reached Lyons two more had died and the last two perished on the final leg of the journey to Paris. Wright later wrote: “I have wondered several times since, what became of these two….the bottle had on it a label with their name and country, and I left it behind me in the railway carriage.”
In 1933 an American ichthyologist, George Sprague Myers, decided that the gourzon from Seychelles and its relatives in Madagascar should not belong to the genus Haplochilus, and he created a new genus, Pachypanchax, for them – “pachy” from a Greek word meaning “big” and “panchax” being the name of a related group of fishes: the “big panchax”, if you will. Myers must have known what he was talking about because his PhD thesis was about the fishes in the gourzon family!
Today, the gourzon is a threatened species. The streams where it lives are being polluted, diverted, invaded by alien species like the Mozambique tilapia and the guppy, or destroyed by concrete channelisation. Other threats are sedimentation caused by erosion, and deforestation along streams, which leads to increased exposure to sunlight causing the water to heat up and even dry up during periods of little rainfall. Troubled waters indeed!
After all this, you will not be surprised if I tell you that one of my favourite postage stamps is the SR3.50 one that was issued in 2000. It is not one of our most colourful stamps, but there is something quite touching about the way the gourzon in the picture is poised, just before it lunges forward, its eyes seeming to stare apprehensively, and one can imagine the red-spotted fins quivering – as I watch them do as the fish in my mother’s aquarium wait to be fed. 88 million years ago, Madagascar became detached from the continental mass made up of Seychelles and India. It must have been at that moment that the gourzon in Seychelles and Madagascar began to evolve into different species. Think of that next time you stand by a stream where gourzon still live.
Island Conservation Society promotes the conservation and restoration of island ecosystems.
by Pat Matyot