The silver cyprinid (''Rastrineobola argentea'') also known as the Lake Victoria sardine, mukene, and omena (native language), dagaa (Swahili) is a species of pelagic, freshwater

ray-finned fish Actinopterygii (; ), members of which are known as ray-finned fish or actinopterygians, is a class of bony fish that comprise over 50% of living vertebrate species. They are so called because of their lightly built fins made of webbings of sk ...

in the danio

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Danionidae The danionins are a group of small, minnow-type fish belonging to the family Danionidae. Species of this group are in the genera clades ''Danio'' and '' Devario'' (which also includes ''Chela'', ''Laubuka'', ''Microdevario'', and ''Microrasbora ...

from East Africa. It is the only member of the

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

''Rastrineobola''.

Description

A small silvery fish which has a strongly compressed body covered in large scales with a pearlescent sheen and a yellow tail, and can grow to a length of . The lateral line is below the midpoint of the body and runs to the lower part of the caudal peduncle. The cheek is covered by delicate suborbital bones.

Distribution

The silver cyprinid is known from the drainage basins of Lake Kyoga, Lake Nabugabo and the

Victoria Nile The White Nile ( ') is a river in Africa, the minor of the two main tributary, tributaries of the Nile, the larger being the Blue Nile. The name "White" comes from the clay sediment carried in the water that changes the water to a pale color. ...

that are located in Uganda, and

Lake Victoria Lake Victoria is one of the African Great Lakes. With a surface area of approximately , Lake Victoria is Africa's largest lake by area, the world's largest tropics, tropical lake, and the world's second-largest fresh water lake by surface are ...

that is shared by

Kenya Kenya, officially the Republic of Kenya, is a country located in East Africa. With an estimated population of more than 52.4 million as of mid-2024, Kenya is the 27th-most-populous country in the world and the 7th most populous in Africa. ...

Uganda Uganda, officially the Republic of Uganda, is a landlocked country in East Africa. It is bordered to the east by Kenya, to the north by South Sudan, to the west by the Democratic Republic of the Congo, to the south-west by Rwanda, and to the ...

and

Tanzania Tanzania, officially the United Republic of Tanzania, is a country in East Africa within the African Great Lakes region. It is bordered by Uganda to the northwest; Kenya to the northeast; the Indian Ocean to the east; Mozambique and Malawi to t ...

Biology

The silver cyprinid has a lake-wide distribution covering both inshore and offshore in Lake Victoria. It normally occurs between in depth, although both eggs and fry can be encountered as deep as . The adult fish stay close to the bottom in daytime and rise up towards the surface at night. The juvenile fish move away from the shore where they spend their larval stage in shallow water. In Lake Kyoga this species is found in open water apparently avoiding the water-lily swamps and it is normally caught in turbulent areas of the Victoria Nile. Its diet consists mainly of

zooplankton Zooplankton are the heterotrophic component of the planktonic community (the " zoo-" prefix comes from ), having to consume other organisms to thrive. Plankton are aquatic organisms that are unable to swim effectively against currents. Consequent ...

and insects caught on the water surface. It is predated on by birds and the catfish '' Schilbe mystus'', '' Clarias gariepinus'' and '' Bagrus docmak''. It is thought that spawning occurs inshore and a mature female may have an estimated fecundity of >1,000 eggs. The eggs are planktonic. The silver cyprinid breeds throughout the year with two peaks, the first in August and the second in December-January. It is fast growing and reaches sexual maturity at ages which vary from 16 to 25 months. The silver cyprinid is parasitized by the fish

cestode Cestoda is a class of parasitic worms in the flatworm phylum (Platyhelminthes). Most of the species—and the best-known—are those in the subclass Eucestoda; they are ribbon-like worms as adults, commonly known as tapeworms. Their bodies co ...

'' Ligula intestinalis'' and this parasite causes changes in the adult fishes' behaviour in that they remain with the juveniles on the surface and undertake horizontal movements to and from the shores. In the mid-morning the parasitised fish have a tendency to move towards the shoreline, especially where there are sandy beaches, to search for food. The juveniles feed on zooplankton such as copepods and young stages of planktonic chironomids while the parasitised adults prefer insect larvae and shore dwelling adult insects such as corixid bugs. After nightfall the surface dwelling parasitised fish mix with the health adults when they move up the water column to top waters of the lake. The silver cyprinid is the only native fish species which has remained abundant in Lake Victoria since the introduction of the Nile perch, ''

Lates niloticus The Nile perch (''Lates niloticus''), also known as the African snook, Goliath perch, African barramundi, Goliath barramundi, Giant lates or the Victoria perch, is a species of freshwater fish in family Latidae of order Perciformes. It is wides ...

'' and Nile tilapia '' Oreochromis niloticus'' to the lake. These two species have almost wiped out the native zooplankton-eating haplochromine

cichlid Cichlids () are a large, diverse, and widespread family of percomorph fish in the family Cichlidae, order Cichliformes. At least 1,760 species have been scientifically described, making it one of the largest vertebrate families, with on ...

s thus reducing competition for this species.

Fishery

Dagaa/mukene/omena is an important fish for Lake Victoria fishermen. It is caught using light attraction during moonless nights.

Food

Dagaa/mukene/omena from Lake Victoria is an important fish in the diet of people in eastern and southern Africa. The fish is caught during moonless nights and in the morning it is sold to women who spread it out for drying in the sun. This takes one day or more, depending on the weather. Unfortunately, the best catches are made during the rainy season when drying is difficult resulting in lower quality of the dried product. The lowest quality is however still usable as chicken feed. Drying is often done on the sand, on rocks or on old nets spread on the grass. Drying racks have not caught on, neither have salting or smoking. The dried fish is packed in sacks and traders take the fish to the market. A major wholesale market for dried dagaa is in Mwanza, Tanzania, and Kisumu Kenya, from where it is transported all over eastern and southern Africa for use as food or chicken feed. Sometimes it competes with dried kapenta which is usually preferred though more expensive.

References

{{Taxonbar, from=Q1851568 Danios Chedrinae Fish of Lake Victoria Fish described in 1904 Taxonomy articles created by Polbot