''Schilbe intermedius'' or the silver butter catfish is a widespread species of African

catfish Catfish (or catfishes; order Siluriformes or Nematognathi) are a diverse group of ray-finned fish. Named for their prominent barbels, which resemble a cat's whiskers, catfish range in size and behavior from the three largest species alive, ...

. It seems closely related to ''

Schilbe uranoscopus ''Schilbe'' is a genus of schilbid catfishes native to Africa. Some are colloquially called butter catfish, though this may also refer to the Asian genus '' Ompok'' of the family Siluridae. Species There are currently 21 recognized species ...

'' and these two species are sympatric over part of their ranges.

Distribution

Widespread in sub-Saharan Africa from the

Senegal River ,french: Fleuve Sénégal) , name_etymology = , image = Senegal River Saint Louis.jpg , image_size = , image_caption = Fishermen on the bank of the Senegal River estuary at the outskirts of Saint-Louis, Senegal ...

across to

Somalia Somalia, , Osmanya script: 𐒈𐒝𐒑𐒛𐒐𐒘𐒕𐒖; ar, الصومال, aṣ-Ṣūmāl officially the Federal Republic of SomaliaThe ''Federal Republic of Somalia'' is the country's name per Article 1 of thProvisional Constitut ...

and south as far as the Pongola River in

South Africa South Africa, officially the Republic of South Africa (RSA), is the southernmost country in Africa. It is bounded to the south by of coastline that stretch along the South Atlantic and Indian Oceans; to the north by the neighbouring count ...

Biology

''Schilbe intermedius'' is a potamodromous catfish. It is reported to be a

pelagic The pelagic zone consists of the water column of the open ocean, and can be further divided into regions by depth (as illustrated on the right). The word ''pelagic'' is derived . The pelagic zone can be thought of as an imaginary cylinder or w ...

species which occurs mainly in shallow waters and open waters of lakes, it migrates to the surface at night. Generally found in the lower reaches of river systems. It feeds on a fish, either swallowed whole or in pieces and a wide range of invertebrates including terrestrial insects. It is mainly piscivorous once it reaches 13–34 cm in length. ''Schilbe intermedius'' rarely grows to lengths greater than 30 cm. It breeds throughout the year peaking in the rainy season when it migrates into rivers in fairly compact schools to spawn in floodwater pools. In one study the most common prey item was redeye barb, a

cyprinid 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 ve ...

, which made up 29% of all identifiable fish species sampled from the catfishes stomachs.

Description

There are two populations of the species one with and one without an

adipose fin Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as s ...

. The population lacking an adipose fin are from the north and west of Africa while the populations with an adipose fin are from the central, east and south of Africa. Quite distinctive with a large shovel mouth surrounded by 4-6 nasal barbs and the eyes slightly protrude from head. The

anal fin Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as s ...

is long, extending from vent almost to the

caudal fin Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as s ...

. It has four pairs of short, barbels around the mouth. The ground colour is silvery, brownish to olive on the back and upper parts of the head. There are two dark grey to olive bands, the longest running along the lateral line from the upper gill cover to the caudal peduncle, where this band starts on the upper gill cover there is a dark humeral spot. The second shorter band runs from the beginning of the pectoral fins to the end of the

. The fins are transparent, although the anal fin has a dark band near the body and there is a dark streak which runs into each lobe of the deeply forked

Fisheries

''Schilbe intermedius'' is fished for food but tends not to be the primary target for fishermen who usually catch it when hunting for other species.

References

{{Taxonbar, from=Q3642172 intermedius Fish described in 1832