I would hazard a guess that the fishkeeping careers of a large proportion of the readers of this bloggo started with the humble guppy. A strikingly attractive, and ridiculously hardy little fish, specimens can be purchased for well under a quid in any petshop in the land. It is a native of north-eastern South America north of the Amazon, and some of its offshore islands (the Leeward Islands, Trinidad, and Barbados in the Windward group) from where it has been introduced to many West Indian islands to control mosquitoes. It was introduced into North America for the same purpose in 1908 and to Hong Kong in the years just after WW1. All this is well known, but what is less well known is that there are, or at least were guppies living wild in the UK.
According to Sir Christopher Lever, the world`s expert on the subject of naturalised animals, during the 1970`s there were at least two colonies of these hardy little tropical fish living wild in the United Kingdom. But how is this? you might well ask. The more eco-concerned of you might start to rant about the abominable effects of global warming, but in fact the tale has a far less portentious explanation.
Between July 1966 1966 and February 1968, zoologist B.S.Meadows carried out a study into a naturalised population of guppies that were living in a stretch of the River Lea which runs through Hackney in north-east London, where the temperature of the water had been raised to an ideal height for these tiny South American fishes. Ironically the population only surviveds because that portion of the river was so polluted that the only remaining native fish was the three spined stickleback which did not pose a threat to the burgeoning population of tropical livebearers.
When he wrote his seminal book “The Naturalised Animals of the British Isles” in 1975, Sir Christopher Lever noted sadly, that although the gradual clean-up of the river could only be a good thing environmentally speaking, it would probably mean the end of the River Lea`s population of guppies as larger, predatory species recolonised their old haunts, and munched away at the dwindling population of tropical interlopers.
History doesn`t relate whether Lever`s dismal predictions were right or not, because around about 190 the old coal powered power station was closed down for good, and whether or not there were any siurviving guppies in the river, they would certainly have died out when the water temperature returned to normal.
The other population of British guppies has an even morte interesting – and tragic – history. In 1963, a pet shop in Lancashire went out of business and the proprietor, hearlessly threw all his stock of tropical fish into the St Helen`s Canal, where they would undoubtedly have died very quickly had a 400 yard stretch of the waterway not been heated to an ideal temperature for tropical fish by the discharge from the nearby Pilkington Brothers Glass Factory.
According to Lever, a viable breeding population of guppies and also of Red Bellied Tilapia (Tilapia zillii) was soon established along with non breeding populations of angel fish, mollies and an un-named species of tropical catfish. According to Leslie Bromilow, the secretary of the St Helen`s Angling Association, this stretch of canal became known as “The Hotties” and the tropical intruders survived happily there for many years.
However, this story too has an unhappy ending. Leslie told us wryly: “unfortunately about ten years ago they switched the pumps off and the water cooled down and all the fish dies, but there is still a thriving population of Red Eared Terrapins”.
We spoke to the press office at Pilkington Brothers who confirmed Leslie`s story, and although they bemoaned the fact that they had destroyed the country`s only surviving wild population of tropical fish, they were not at all impressed by our suggestion that the least that they could do was to release thirty quids worth of guppies back into the water and start again.
So there you have it? Is the guppy (and the red bellied tilapia) finally extinct in the UK or are there other serendipitously introduced populations lurking in areas where industrial activity has inadvertantly provided an environment where they can live and thrive?
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