Neolamprologus pulcher. Photograph from TFH Archives.
By David E. Boruchowitz
Cichlids demonstrate extremely sophisticated reproductive strategies. One of the least common involves cooperative breeding in groups or colonies. Lake Tanganyikan Neolamprologus pulcher breed en masse, with the entire colony rising as one to fend off predators, and with non breeding individuals participating in the care and protection of the offspring.
Aquarists have long known about this behavior, which is more obvious in the wild, where hundreds of fish are involved, but which translates in captivity into breeding groups that avoid the typical predation on the fry by non parental adults in the same tank.
A new study reveals that about 10 percent of the fry produced in these colonies are sired by subordinate males, and that those males are more diligent in protecting the young.
This is reminiscent of the situation in several Xiphophorus swordtails, where smaller, inconspicuous males rely on sneaking rather than courtship to father a small percentage of fry. In both cases subordinate males father a small but significant number of offspring, though in the case of the swordtails it is a matter of genetic castes among the males, not just one of dominance.
Ted Judy's 75-gallon tank featuring cichlids and swordtails. Photograph by Ted Judy.
Many Mexican and Central American cichlids share their habitats with various species of swordtails. Many hobbyists think the combination is either difficult or impossible to replicate in captivity—and it certainly doesn’t help that many cichlid fans see swordtails as live food!
In the November issue’s “Cichlid World” column, Ted Judy showcases his aquarium that proves the combination can not only work, but work well http://www.tfhdigital.com/tfh/201111/#pg29. He makes several key points that are critical to success, including that the cichlid species must not be overly aggressive, large, or a known piscivore. It is also wise to include only adult swords that are not much smaller than the cichlids. Providing plenty of room and hiding places is also a must.
In this particular tank, the swift current is also a critical feature that is easily noticed due to the sideswept substrate and blowing plants. The current was added because the fish come from a well-oxygenated riverine habitat, but it provides the added bonus of allowing the fish to exercise naturally and to expend extra energy. On the downside, the female swordtails must be rotated out of the tank to give birth both because of the fast current and so the fry can escape hungry cichlids.
So the next time you are considering what to put in with your cichlids, try thinking about swordtails—they are not simply feeder fish!