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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
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.
ray-finned fish
Actinopterygii (; ), members of which are known as ray-finned fishes, is a class of bony fish. They comprise over 50% of living vertebrate species.
The ray-finned fishes are so called because their fins are webs of skin supported by bony or h ...
in the carp family
Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...
, Cyprinidae from East Africa. It is the only member of the genus
Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...
''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 Kyoga,Lake Nabugabo
Lake Nabugabo is a small freshwater lake in Uganda.
Location
The lake is in Masaka District, Central Region of Uganda, approximately , by road, east of the town of Masaka.
Overview
Lake Nabugabo is a satellite lake of Lake Victoria, being onl ...
and the Victoria Nile
The White Nile ( ar, النيل الأبيض ') is a river in Africa, one of the two main tributaries of the Nile, the other being the Blue Nile. The name comes from the clay sediment carried in the water that changes the water to a pale color. ...
, occurring in Kenya
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, Uganda
}), is a landlocked country in East Africa. The country 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 south by Tanzania. The sou ...
and Tanzania
Tanzania (; ), officially the United Republic of Tanzania ( sw, Jamhuri ya Muungano wa Tanzania), is a country in East Africa within the African Great Lakes region. It borders Uganda to the north; Kenya to the northeast; Comoro Islands ...
.
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 ofzooplankton
Zooplankton are the animal component of the planktonic community ("zoo" comes from the Greek word for ''animal''). Plankton are aquatic organisms that are unable to swim effectively against currents, and consequently drift or are carried along by ...
and insects caught on the water surface. It is predated on by birds and the catfish '' Schilbe mystus'', ''Clarias gariepinus
''Clarias gariepinus'' or African sharptooth catfish is a species of catfish of the family Clariidae, the airbreathing catfishes.
Distribution
They are found throughout Africa and the Middle East, and live in freshwater lakes, rivers, and sw ...
'' 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 ''Ligula intestinalis
''Ligula intestinalis'' is a cestoda, tapeworm of fish, fish-eating birds and copepods, with species from each group featuring in its complex Biological life cycle, life cycle. ''Ligula intestinalis'' is a parasite that changes its intermediate ...
'' 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 chironomid
The Chironomidae (informally known as chironomids, nonbiting midges, or lake flies) comprise a family of nematoceran flies with a global distribution. They are closely related to the Ceratopogonidae, Simuliidae, and Thaumaleidae. Many specie ...
s 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'' and Nile tilapia '' Oreochromis niloticus'' to the lake. These two species have almost wiped out the ende zooplankton eating haplochromine cichlids 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