The silver cyprinid (''Rastrineobola argentea'') also known as the Lake Victoria sardine, mukene,and omena (native language), dagaa (swahili language) is a species of pelagic, freshwater ray-finned fish in the carp family,

Cyprinidae Cyprinidae is a family of freshwater fish commonly called the carp or minnow family. It includes the carps, the true minnows, and relatives like the barbs and barbels. Cyprinidae is the largest and most diverse fish family and the largest verte ...

from East Africa. It is the only member of the genus ''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 basin of

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 tropical lake, and the world's second-largest fresh water lake by surface area after ...

Lake Kyoga Lake Kyoga (literally 'the place of bathing' in Runyoro language) is a large shallow lake in Uganda, about in area and at an elevation of 1,033 metres. The Victoria Nile flows through the lake on its way from Lake Victoria to Lake Albert. The mai ...

, Lake Nabugabo and the Victoria Nile, occurring in Kenya, Uganda and Tanzania.

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 and insects caught on the water surface. It is predated on by birds and the catfish ''

Schilbe mystus The African butter catfish (''Schilbe mystus'') is a species of fish in the family Schilbeidae. It is native to many major river systems in Africa. Other common names for the fish include butter fish, butter barbel, African glass catfish, luban ...

'', '' Clarias gariepinus'' and ''

Bagrus docmak ''Bagrus'' is a genus of bagrid catfishes. These are relatively large catfish found in freshwater habitats in Africa, except for the virtually unknown ''B. tucumanus'' from South America, which likely is a synonym of '' Luciopimelodus pati''. ...

''. 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, known as tapeworms. Their bodies consist of man ...

Ligula intestinalis ''Ligula intestinalis'' is a tapeworm of fish, fish-eating birds and copepods, with species from each group featuring in its complex life cycle Life cycle, life-cycle, or lifecycle may refer to: Science and academia *Biological life cycle, th ...

'' 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 Copepods (; meaning "oar-feet") are a group of small crustaceans found in nearly every freshwater and saltwater habitat. Some species are planktonic (inhabiting sea waters), some are benthic (living on the ocean floor), a number of species have p ...

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 wid ...

'' and Nile tilapia ''

Oreochromis niloticus The Nile tilapia (''Oreochromis niloticus'') is a species of tilapia, a cichlid fish native to the northern half of Africa and the Levante area, including Israel, and Lebanon. Numerous introduced populations exist outside its natural range. It ...

'' to the lake. These two species have almost wiped out the ende zooplankton eating

haplochromine __NOTOC__ The haplochromine cichlids are a tribe of cichlids in subfamily Pseudocrenilabrinae called Haplochromini. This group includes the type genus (''Haplochromis'') plus a number of closely related genera such as '' Aulonocara'', '' Astat ...

cichlid Cichlids are fish from the family Cichlidae in the order Cichliformes. Cichlids were traditionally classed in a suborder, the Labroidei, along with the wrasses ( Labridae), in the order Perciformes, but molecular studies have contradicted this ...

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 Cyprinid fish of Africa Fish of Lake Victoria Fish described in 1904 Taxonomy articles created by Polbot