Trouble With Hybrids

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.