Unlikely though it may seem, some cichlids can actually remove snails from their shells before swallowing them. Others can make females “cough up” their babies—and then they eat them.
Cichlids form one of the largest and most varied families of freshwater fish known to science. Some are as small as a paperclip, and others are as large as a small shark. Some are circular, like a dinner plate, and others are thin, like a pencil. Despite the wide range of sizes, shapes, colors, and behaviors found in cichlids, there is one unusual feature that is common to them all.While the vast majority of fish have two nostrils on each side of the head, cichlids have just one nostril on each side. Nevertheless, they still have a keen sense of smell— they just manage with half the number of nose openings of other fish. If they did not have a single nostril, it would be difficult to accept that some of the fish known as cichlids actually belong to this family.
Cichlid species have evolved some very clever ways of protecting their eggs and young from predators. Many species stick their eggs to a leaf, a branch, a stone, or the roof of a cave. Sometimes they lay them in a pit. Some even use an empty snail shell as a “cave.” In all these species, one or both parents then stand guard over their eggs and newly hatched young.These particular species are known as substrate spawners. In others, protection is taken further. Spawning takes place in a shallow pit dug by the male, just as in many other cichlids.However, this pit does not act as a nest. Instead, it is merely a spawning site. As the eggs are laid, the female carefully picks them up in her mouth and, when spawning has been completed, she swims off with the whole batch safely tucked away. She will keep these eggs inside her mouth until they hatch out. When they are ready to hatch, she releases her babies into the water, but continues to watch over them carefully. She takes them back into her mouth at the first sign of danger.These species are known as mouth brooders.
Freshwater “Coral Reef” Fish
Many cichlids are brightly colored, none more so that those found in the great rift lakes of Africa.Among these, the rock-dwelling cichlids, or mbuna, of Lake Malawi, are the freshwater equivalents of the colorful coral reef fish found in tropical seas. The African rift lakes are true inland seas because they are so large and deep. Lake Tanganyika, for instance, is nearly 430 miles long, 85 miles wide, and 4,800 feet deep. Lake Malawi is 350 miles long, 50 miles wide, and 2,300 feet deep. Lake Victoria is the shallowest, but is the one with the largest surface area of all. It is 200 miles long,185 miles wide, and 145 feet deep.Only two other inland seas are larger than Lake Victoria: Lake Superior and the Caspian Sea. Such large bodies of water are extremely rich in fish species and have many different habitats for them to occupy.The lakes are also virtually cut off from the outside world. As a result, the species that live there have evolved their own unique characteristics.These fish are termed “endemic”—in other words, they are not found anywhere else.
Nile Perch Disaster
Sadly, a great many of the cichlids that are endemic to Lake Victoria have been wiped out.This loss of cichlids was caused by the introduction of a large predatory fish, the Nile perch, into the lake in the 1950s and 1960s.The Nile perch was introduced as a source of food for the people who live by the lake.However, it ate huge numbers of the cichlids in the lak —possibly as many as 50–90 percent of them according to some sources. As the stocks of cichlids dwindled, the Nile perch found other foods, such as shrimp, other fish, and even its own young. Eventually, a balance was achieved between the various species living in the lake. Unfortunately, part of the cost of reaching this balance in Lake Victoria However, it soon became obvious that many species could be bred easily in aquariums.Therefore, very soon, the percentage of captive-bred cichlids increased dramatically. It was also noted that some species appeared in different color and fin varieties.These were selected and developed further, and the popularity of cichlids rocketed.Two types of cichlid, angelfish and discus, proved to be the best species for producing different varieties. As a result, numerous variations of both these fish are available, and far fewer are now collected from the wild. The same techniques have been applied to other types of cichlids, such as the African rift lake species. However, these fish are so spectacular and variable anyway that they have not been developed to the same extent as angelfish and discus. has been the extinction of many species, including the cichlids.
Popular Aquarium Fish
Because such a wide range of attractive species is available, cichlids have been popular aquarium fish for over a hundred years.At first, all of them were collected from the wild.