Hybrids, by Kevin Thurston

Hybrids

by Kevin Thurston
From CAS Newsletter and Aquarist, Colorado Aquarium Society
Aquarticles.com

The rules for most typical society bowl shows as well as auctions usually have somewhere buried amongst them a simple statement that reads something like the following: “No Hybrids”. This rule is ostensibly placed there because there’s something in the club constitution about preserving natural species and being responsible aquarists and other such moral pronouncements that sound good on paper, but are rarely followed by hobbyists regardless of if they are society members or not. As I intend to point out, the no hybrids rule really means “No hybrids that we disapprove of. Other hybrids are perfectly welcome”.

First let’s establish exactly what a hybrid is.
Here’s a definition from one of my favorite web sites, www.dictionary.com :
hy·brid 1. Genetics. The offspring of genetically dissimilar parents or stock, especially the offspring produced by breeding plants or animals of different varieties, species, or races.
That leaves it pretty wide open doesn’t it? By the way, if you read the classified ads for pets in most newspapers, you’ll see where either the advertiser or the person taking the ad over the phone misunderstood and the ad reads “high bred”. Anyway, back to the matter at hand. Although the definition above leaves things pretty wide open, most of us in the hobby understand hybrid to mean a cross between two different species. That opens another can of worms since nobody can come up with a definition of species that holds up in every case. Be that as it may, let’s proceed as if we agree on what constitutes a species. What are the most common hybrids in the hobby today?

I believe the most common hybrids in the hobby are found amongst the livebearers.
There are few livebearers in the hobby that aren’t hybrids, though admittedly there are a few wild type green swords or montezuma swords showing up at auctions here and there. The swordtails and platys in shops that are seen in multiple color varieties are all hybrids of Xiphophorus helleri, X. variatus and X. maculatus. The fancy mollies are mostly hybrids of Poecilia sphenops, P. latipinna and P. velifera with possibly some others thrown in. These seem to be approved hybrids and are typically seen and welcomed at society functions. What about fancy discus? Since these rarely have any Symphysodon discus genes in them and are usually just highly developed strains of S. aquefasciata (with possibly some sub-species mixed!) I don’t consider them to be hybrids, but I suspect that some could make a cogent argument that they are. Since these are seen at society functions, they must be either approved hybrids or not hybrids at all. What about fancy gouramis? While I am aware of some hybridization that has occurred in the past between some species of Colisa (see page 502 of the 19^th edition revised of Exotic Aquarium Fishes by William T. Innes) I really don’t know how the modern fancy strains of dwarf gouramis were achieved, so I can’t say if they are hybrids or not. The gold gourami is simply a highly bred strain of Trichogaster trichopterus as is the opaline gourami. Wild T. trichopterus are tan fish sometimes seen as the 3 spot gouramis. What about a cross between a gold gourami and an opaline gourami? That would fit the dictionary definition of a hybrid, but wouldn’t be a cross between species. Whether hybrid or not, the fancy gouramis seem to be on the approved list, probably because no one seems to know if they are really hybrids or not.

What about naturally occurring hybrids?
First you have to know something about the fish involved to determine if they really are a hybrid or not. Some years ago, there appeared in the shops a catfish that was almost always labeled as hybrid shovelnose cat. Had they bothered to look up the fish they would have been able to identify it as Hemisorubim platyrhynchus which is not a hybrid. Lately I’ve seen advertisements on the internet for a catfish that is being sold as a hybrid between the red tailed catfish Phractocephalus hemioliopterus and the tiger shovelnose Pseudoplatystoma fasciata. Since these are separate genera and neither is commercially raised, it is doubtful that these are actually hybrids, but merely an unidentified species (although recent information indicates that they may be developed through artificial insemination, stripping the parents of gametes and mixing them). Hybrid marine fish in the hobby are very improbable, but there’s an example. Townsends angel, known either as Holocanthus townsendi or Angelichthys townsendi is a naturally occurring hybrid of the blue angelfish, H. bermudensis and the queen angel H. ciliaris. While there are not many of these in the hobby, I doubt that they would be turned away from a society function, most likely because the judges would be unaware that it is a hybrid. There are a few other naturally occurring hybrids which do not come to mind, but are unlikely to be seen in the hobby.

What about hybrid cichlids?
Now here’s where we really get into a scrape! The rancor shown toward hybrid cichlids is phenomenal. Look at one of the latest, the colored parrot cichlid. This is purported to be a hybrid between the red devil, Veija labiatum or perhaps the midas cichlid V. citrinellum and the severum Heros severus, however the origins of this fish have not been revealed. This fish seems to be universally reviled by the cichlid devotees, probably not just because of their hybrid status, but also because they are typically sold as dyed fish. Despite being universally reviled by the cichlid buffs they seem to enjoy enormous popularity amongst the general hobby if sales are any indication. By the way, if you want to see how even the so called experts are confused about hybrids, there was an article in a well known aquarium magazine a few years back. In this article, the author was describing his attempts to breed parrot cichlids. He seemed to claim definite knowledge that they were hybrids between severums and red devils. Oddly enough, it didn’t seem to occur to him that these hybrids might be sterile as any farm boy who has worked with mules knows that most hybrids are sterile. What’s even worse is that he wrote that if there were any offspring, Mendelian genetics dictated that 25% of them would be severum, 25% would be red devil and 50% would be parrot cichlids. Mendelian genetics applies to single traits such as the height of pea plants and eye color in humans. It does not apply to hybrids. This blunder points to one of the reasons that hybrids are frowned upon, which is you can’t get the original species back from breeding hybrids.

Another more recent hybrid is the one known as flowerhorn. Again the Asian breeders are keeping the origin of the fish a secret, but they make no bones about it being a hybrid. This fish has not been so popular as the parrot, probably because the prices on them have been ridiculously high, although more affordable prices are being seen lately. This is a hybrid that has dubious acceptance at society functions.

The real abhorrence for hybrids amongst the cichlid crowd has more to do with hybrid African cichlids than with the American hybrids discussed so far.
Early in the cichlid hobby, many hobbyists would set-up an African cichlid tank with a bunch of rocks and a bunch of Mbuna. When a female was seen holding eggs or fry, they would be caught and stripped, but this procedure was easier said than done. Often the females would be left in the tank and the fry were left to their own devices among the rocks, frequently evading the adults which were poor predators to begin with. So the fry would often appear in the tank and their heritage was completely unknown. Sometimes the fry would not look exactly like any of the adult fish and they might be presumed to be hybrids. Other times, separate species would be seen spawning so the fry were known to be hybrids. In any case, this offended the sensibilities of the hobbyists who saw themselves as preserving these high priced fish. Now days we realize that even though these fish have a low fecundity, they are very prolific. We have nothing to worry about as far as the survival of things like zebras, Labeotropheus species and other Mbuna surviving in the hobby, yet the hybrid African cichlid is usually not welcomed at society functions. As easily as rift lake cichlids hybridize in captivity, how do we know that there aren’t several naturally occurring hybrids among them?

If you’ve stuck with this article this long, you should have seen how some hybrids are accepted at society functions while others are not. My contention is that there is a prejudice against hybrids that is not maintained in all cases and is totally arbitrary. If a hybrid can be readily purchased at a store, does that make it more acceptable than the result of a cross in a fellow hobbyist’s tank? Apparently so, unless that fish offends our sensibilities as the parrot cichlid does. I suspect that many hobbyists are unaware that they are supporting hybridization when they purchase certain fish, just as the proclaimed vegan is blissfully unaware that they are supporting the beef industry when they drive a car that has tires as well as many other items that include beef by-products in their manufacture.