The Trouble With Hybrids
by Andrew Boyd
First published in Tank Talk, Canberra and District Aquarium Society, Australia
Aquarticles
With all the recent kerfuffle about hybridised cichlids, I thought it timely to write
about why, in certain circles, the word ‘hybrid’ is frowned upon.
There is a perfectly legitimate scientific reason for hybridising fishes (or birds, for
that matter) of different species or genera. One of the old tests of whether or not two
animals would fit into the same genus was to cross breed them and see if the offspring
were fertile. But when trying to preserve dwindling stocks of rare cichlids, hybridisation
is of no good whatsoever, and can even be quite harmful.
An aquarist may have a nice male Melanotaenia goldii, a rare New Guinean
Rainbowfish. But perhaps he cannot find a female of this species and so is tempted to use
a very similar looking female of M. herbertaxelrodi. So he cross breeds the-two
species and obtains a batch of fry that are goldii x herbertaxelrodi hybrids.
Some of these he then sells to friends as goldii and the rest he grows up and
disposes to the aquarium trade. What has he done wrong? Well for a start, his friends will
be in possession of viable hybrids that they will be tempted to rear up and breed, goldii
being as rare as it is. Other aquarists will purchase them from the shops in good
faith and taking them to be pure stock, will also breed them. But these fish are not goldii
at all and at some stage (maybe in the next generation, when the fry will not look like
their parents) someone will work this out. The ultimate result will be a lot of wasted
work in raising fishes of no real value.
Hybridisation is not always deliberate: with the Aulonocara (Malawi Peacock
Cichlids), most of the females are quite similar and in a community tank, the father of a
particular brood of fry may not belong to the same species as the mother. Care must also
be taken in this regard (similar females) with Killifish.
In the Australian cichlid scene at the moment, there is a great deal of concern about
hybridisation because of the low available gene pool, that many dedicated breeders are
devoting their lives to preserving. In the case of many of the Lake Victoria cichlids,
which are now extinct in the wild, this work is quite literally of vital importance.
When buying cichlids, aquarists should make a point of getting to know what wild
specimens look like, to guard against obtaining hybrids, or even 'pure' fish that may not
be compatible with others in their breeding tanks. In the case of the African Rift Lake
Cichlids, the club library has two excellent books by Ad Konigs, on the Malawi and
Tanganyika species, respectively. These works give a good idea of what the fishes look
like in the wild. It is a shame that no such book exists, showing all of the different
populations of Australian Rainbowfishes. All the same, it is a good rule not to cross
breed populations of such variable species as Melanotaenia tilfasciata, but
rather to recognise and work within populations, such as those from the Goyder and Giddy
Rivers.
Be wary of so-called 'new' species of fishes just on the market for the first time in
many years. There have been cases of unscrupulous breeders deliberately crossing different
species (particularly in the New Guinean Rainbowfishes and African Cichlids) in order to
produce something more colourful. They then raise the hybrids and search, meantime, in the
handbooks for something approximating their appearance. The hybrids are then released
under this appealing name, to an unsuspecting public always on the lookout for something
new and prepared to pay exorbitant prices. To be sure, some new fishes are smuggled into
the country occasionally, but many people have been 'caught' by flashy hybrids that
appeared to be prohibited species at the time.
However, the major trouble with hybrids is that they divert those serious souls who are
trying to preserve what is left of cichlids that were formerly allowed into Australia. For
once these populations are gone, we shall never see them again, except as pictures in old
books! A while ago, I was privileged to hear a talk by Graeme Phipps (Curator-in-Chief,
Taronga Park Zoo), who expressed the opinion that hybridisers of rare and provenanced
(place of origin known) stocks were committing a "crime against the species" and
should be prosecuted accordingly. So please do not hybridise fishes deliberately and
ensure that you take every precaution to prevent its happening accidentally, thereby
helping our hobby to survive.
See also: Flowerhorns, alias Nightmares, by Madhu Sudhanan
Inbreeding Tropical Fish. Good or Bad? by Bill Forrest
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