The creation (deliberate or accidental) of hybrids is an important and controversial issue with cichlid aquarists. Here are my views.
Quite frequently, an aquarist will write to me to describe how two of his or her cichlids have spawned, but the surprising thing is that the aquarist thought the fish were two different species. The question typically goes something like this: "My male species 1 just spawned with my female species 2. Have you ever heard of this, and what should I do to raise the kids?" Other variants include "Will I get rich selling these?" and "What would be their proper name?"
These questions raise some interesting and deep philosophical and ethical questions. I will address these issues by trying to answer some of the specific questions.
First, some terms. "Hybrid" refers to the result of mating a male of one species with a female of another species. We often call this "crossing" two species.
1. Have I ever heard of this before?
This is easy to answer. Yes I have. Hybrids are quite common in the cichlid hobby. Almost any Central American cichlid will hybridize with any other. Many of the mbuna (rock dwelling cichlids from Lake Malawi) will hybridize with each other. I have even heard of a mouthbrooder hybridizing with a substrate-spawning cichlid. So, hybridization is not rare.
2. Does this occur in the wild?
This is difficult to support with data, but from my many years of observations in the field in Central America, and from what I have read and heard from fellow cichlid researchers working elsewhere, hybrids are very rare in the wild. Surprisingly, two species of fishes which together in the wild will not hybridize, will do so in an aquarium quite readily.
3. Will I get rich producing hybrids?
No. In fact, you will find that most advanced cichlid hobbyists have an active dislike for hybrids (and to be honest, for the people that produce them).
Every now and then someone produces a new "wonder" fish by hybridizing two species and they may even sell some. In the end, however, this person usually finds themselves shunned by the rest of the cichlid aquarist community and worse yet, the person gets a bad reputation even if they stop producing hybrids: their future actions are always suspect. A bad reputation is an extremely difficult thing to change.
4. What is the proper scientific name of a hybrid?
Manmade hybrids do not get a new scientific name, in other words, you cannot create a new species by hybridization in your fish tank.
Rather, we indicate hybrids by identifying the two parental species. For example, if you crossed a texas cichlid, Herichthys cyanoguttatus with a convict cichlid, Archocentrus nigrofasciatus, the most correct name to use would be Hericthys cyanoguttatus x Archocentrus nigrofasciatus, i.e., the two names joined by an x.
For those who are really up on their biology, what I have said here is only partly true. We now know that many species of plants in the wild, and potentially some animals as well, are actually the result of hybridization in the wild. However, as far as we know at this point, this has not occurred with cichlids in the wild.
5. Why are hybrids so bad?
Hybrids are bad for several reasons at many different levels.
At a philosophical level, many people, myself included, dislike hybrids because the creation of hybrids is a kind of arrogance on behalf of people, namely some sort of deep-rooted feeling that we as humans can improve upon nature. I feel that with 2300+ species of cichlids in the wild, we don't need to go creating yet another kind just because we can. Furthermore, the ability to create "designer" organisms has a way of cheapening the beauty and wonder of real organisms.
For example, here is a picture of a "designer" tinfoil barb which has been tatooed with colors.
There is no reason for the color other than that someone thought it looked good and so they did this to the fish.
Compare that to the image of Tomocichla tuba, a fish native to Costa Rica. The remarkable patterns and colors on this fish are the product of millions of years of natural selection, molding this animal to its environment. Every marking and color on this fish means something and is something for us to marvel at and wonder about.
In addition, on a very practical level, hybrids create enormous problems for fellow fish-keepers, problems that may last for a long time and become intractable. Imagine you cross (make a hybrid) between two species of Central American cichlid, e.g., a convict and a texas cichlid. You know that they are hybrids and you keep them in a tank separate from other cichlids. But over time, events cause this tightly controlled situation to get out of hand.
One of the hybrids may jump into another tank (this happens quite often; ask anyone who maintains a large fish room).
You might sell or give away some of the hybrids and the recipient may not know or remember that the fish is in fact a hybrid. People often bring fish back to pet stores or sell them at auctions and so the hybrid nature of the fish can easily get lost along the way.
The first generation of hybrids (called F1 hybrids) are often easy to spot; they look like a mixture of the two parent species. If two of these F1 hybrids go on to mate, or if one of them is mated to either of the parent species, the offspring (F2 hybrids) create the real problems. Why? Because F2 individuals may look like almost anything in between the two parent species, up to and including looking like either of the parent species. This is a disaster waiting to happen because it means that now you have a fish that looks like a certain species but does not have all the right genes for that species.
Now imagine what happens when these offspring grow up and get back into the mainstream of the hobby. A person (potentially you) buys what looks like a convict cichlid at your local pet store. You are unaware that the fish is actually an F2 convict x texas cross brought in a week ago by someone else. The person who sold the fish to the store forgot to mention that point (we will assume they forgot accidentally, but since most reputable pet stores will not knowingly carry hybrids, some people "forget" to mention that the fish they are selling are hybrids).
Now you put your new convict in with your other convict and for some strange reason, they never reproduce successfully. Or they do reproduce and the kids look kind of strange. Now you have a bunch more hybrids that you have to deal with.
You have probably already witnessed this phenomenon without even knowing it. Many times in fish stores I see a tank labeled "Mixed African cichlids". What exactly does that mean? In some cases it means that the fish store had a few of this and a few of that and they put them together. More typically it means that they do not know what genes are in there. The fish are just colorful, so who cares? Well, many people care. I often get emails from people who buy fish from those tanks and then try to figure out which fish they have. The sad answer is that we can never know. Just because a fish superficially looks like species X does not mean that it is that species.
6. Aren't cichlid hybrids just the same phenomenon as different breeds of dogs?
Many people do not realize that all breeds of dogs are just different forms of the same species. The situation with cichlids is completely different. The different kinds of cichlids are completely different species of animals, so crossing two species of cichlids is not like mating a German Shepherd with a poodle, it is more like mating a German Shepherd with a cat.
7. Dealing with hybrids
The solution here is simple. Destroy them immediately. If you have a difficult time killing a bunch of hybrid eggs, imagine how difficult it will be for you to kill them when they are cute little fry or even young adults. This is a responsibility you take on when you keep fish and you should take it seriously.
Under absolutely no circumstances should you pass hybrids on to someone else unless they are to be used as feeder fish.
8. How can I avoid getting hybrids?
Probably the best way to avoid getting hybrids in the first place is to purchase your fish from a reputable dealer and avoid buying fish from a tank labelled "Mixed African Cichlids".
I find it incredibly reassuring that cichlid hobbyists have and continue to take such a strong stance against hybrids. This is not the case in many other animal-related fields. Because of this attitude amongst cichlid keepers, you can go into a pet store in most any part of the world and be reasonably assured that the cichlid you are buying and bringing home is in fact a representative of a real cichlid species. That is truly remarkable.
Please also look at my page on parrot cichlids. If you want a less-restrained discourse on hybrids, take a look at Philippe Burnel's Museum of Horrors web page (in French).