Kariba tilapia facts for kids
Quick facts for kids Kariba tilapia |
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| Conservation status | |
Scientific classification  |
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| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Actinopterygii |
| Order: | Perciformes |
| Family: | Cichlidae |
| Genus: | Oreochromis |
| Species: |
O. mortimeri
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| Binomial name | |
| Oreochromis mortimeri (Trevawas, 1966)
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| Synonyms | |
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The Oreochromis mortimeri, also known as the Kariba tilapia or kurper bream, is a type of cichlid fish. It used to be grouped with other tilapia, but now it's part of the Oreochromis group. This fish lives in the rivers of south-central Africa. You can find it especially in the middle Zambezi River. Sadly, it is an endangered fish. This is mainly because of another fish, Oreochromis niloticus, which is an invasive species that is spreading quickly.
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What Does the Kariba Tilapia Look Like?
The Kariba tilapia is usually greenish-grey, green-blue, or grey-blue. It has darker spots on each of its scales. Female fish and young males often have one to three dark spots in the middle of their sides. These spots might become clearer when the fish dies.
When male fish are ready to breed, they become very shiny. Their colors change from blue-green to bronze. They also have shiny spots on their back fin (called the dorsal fin) and tail fin (called the caudal fin). The back fin has a red edge, but it's not as bright as in some other tilapia. The tail fin has a thin red band at the end. Older males also have noticeably larger jaws.
Where Does the Kariba Tilapia Live?
The Kariba tilapia lives only in the middle Zambezi River valley. Its home stretches from the Cahora Bassa gorge all the way to the Victoria Falls. It also lives in the Luangwa River and its smaller rivers. You can find this fish in Mozambique, Zimbabwe, and Zambia.
Life and Habits of the Kariba Tilapia
The Kariba tilapia likes to swim in groups, called schools. It is mostly active during the day. This fish can also live in water that is a bit salty.
What Does the Kariba Tilapia Eat?
Its main food is long, thin algae and tiny plant-like organisms called diatoms. It also eats some water plants, insect larvae (like those of flies), other insects, tiny crustaceans (like cladocerans and copepods), small shrimp, worms, and snails.
How the Kariba Tilapia Reproduces
Male Kariba tilapia build a special nest for breeding. It looks like a shallow bowl with a small mound in the middle. They make these nests in areas where the water is less than 4 meters (about 13 feet) deep. The male fish performs a special dance to attract females to his nest.
The female fish lays her eggs, and the male fertilizes them. After that, the female collects all the eggs in her mouth. This is called mouthbrooding. While she is holding the eggs in her mouth, she does not eat. Females carrying eggs might even swim together in groups.
The eggs hatch after about ten days. But the baby fish, called larvae, stay in their mother's mouth for a few more days. Once they have used up the food stored in their yolk sac, the tiny fish start to swim out for short feeding trips. They stay very close to their mother. If they sense danger, they quickly dart back into her mouth.
About two weeks after hatching, the female releases her young fish. They are about 1 centimeter (0.4 inches) long. She lets them go in warm, shallow areas near the river banks. Here, the young fish form small groups and find their own food. After releasing her babies, the female goes back to the breeding area to lay eggs again. Kariba tilapia can breed throughout the entire year.
Why the Kariba Tilapia is Endangered
The IUCN (International Union for Conservation of Nature) lists the Kariba tilapia as Critically Endangered. This means it is at a very high risk of disappearing forever. The biggest threat to this fish is another type of tilapia, Oreochromis niloticus. This fish is an invasive species that has been brought into most of the Kariba tilapia's home range. This happened because of aquaculture (fish farming) and also by people who fish for sport (anglers).
Studies in Lake Kariba show that O. niloticus grows faster than the Kariba tilapia. This gives the invasive fish an advantage in competing for food and space. Researchers also found that O. niloticus is more aggressive towards the Kariba tilapia. The bigger the O. niloticus fish are, the more aggressive they become towards smaller Kariba tilapia. Since O. niloticus grows faster, they are usually the bigger fish.
There are no natural barriers to stop O. niloticus from spreading throughout the Kariba tilapia's habitat. It has already replaced the native Kariba tilapia in many parts of Lake Kariba. This is especially true in areas where fish farms raise O. niloticus, a practice that started in the 1990s.
Why is it Called Mortimeri?
The second part of the fish's scientific name, mortimeri, honors M. A. E. Mortimer. He was a researcher for the Zambian Department of Game and Fisheries. He studied tilapia fish in Zambia and also helped a scientist named Ethelwynn Trewavas visit the Luangwa Valley to study this fish in its natural home.
 | Lonnie Johnson |
 | Granville Woods |
 | Lewis Howard Latimer |
 | James West |
