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FACTSHEETS: January 2024 - no. 331

Zaireichthys pallidus Eccles, Tweddle & Skelton, 2011

t is the first month of 2024 and we bring you a little known small genus of African catfish from the Amphiliidae family, namely Zaireichthys and the "Pale sand catlet" Zaireichthys pallidus. The type species is Zaireichthys zonatus Roberts, 1967.

Zaireichthys pallidus - From the Chobe Rapids at the recreational Centre in Kasane, Botswana

Zaireichthys pallidus - From the Chobe Rapids at the recreational Centre in Kasane, Botswana

Roberts (2003) provided a detailed diagnosis of the subfamily Leptoglanidinae (incorrectly formed by Roberts as Leptoglaninae (Ferraris, 2007)) and the genus Zaireichthys. Briefly, Zaireichthys are small (max. SL <50 mm), soft bodied amphiliid catfishes with stout bony serrated spines in the dorsal and pectoral fins that form a defensive tripod when locked into erect positions (Eccles, D.H et al. 2011).

Zaireichthys pallidus - From the Chobe Rapids at the recreational Centre in Kasane, Botswana

Zaireichthys pallidus - From the Chobe Rapids at the recreational Centre in Kasane, Botswana

Because of their small size, not exceeding 50 mm SL, Zaireichthys were often overlooked by early collectors, or were taken for juveniles of other species and discarded. Thus little material was available for study until collections in southern Africa, reviewed by Jubb (1961, 1967) and BellCross & Minshull (1988), and an electric fishing survey of rivers and streams in Malawi by Tweddle & Willoughby (1978) yielded many specimens that were then attributed to Z. rotundiceps (at that time in the genus Leptoglanis), (Eccles, D.H et al. 2011).

Distrbution: Africa: Known only from the Upper Zambezi up to and including the Barotse Floodplain in Zambia and the Chobe and Kwando rivers, in the area of the Eastern Caprivi, Namibia.

Two species, Z. pallidus and Z. conspicuus occur in the Chobe area of Eastern Caprivi above the Victoria Falls but in different habitats. Zaireichthys kavangoensis is found in the Kavango river which runs into the swamps of the Okavango Delta, which is, from time to time, connected to the Kwando River in the Chobe system by the Selinda (Makwegana or Magwegqana) Spillway (Wilson & Dincer 1976). These areas were connected via Lake palaeo-Makgadikgadi about 50 000 years BP (Joyce et al. 2002).

Abstract: Species in the genus Zaireichthys in the amphiliid subfamily Leptoglanidinae characteristically live just above and in fine sand in flowing water. The discovery of a distinct species living in empty Lanistes and Bellamya snail shells in Lake Malawi led to a review of the southern African museum collections of the Zaireichthys, previously lumped together under the name Z. rotundiceps, resulting in several new species being recognised. In this paper, eight new species from southern Africa are described, although recent collections have revealed more new species that require further investigation, particularly in northern parts of the Zambezi system and in eastern Africa (Eccles, D.H et al. 2011).

Common Name

Pale sand catlet

Synonyms

None

Family

Amphiliidae

Subfamily

Leptoglaninae

Distribution

Africa: Known only from the Upper Zambezi up to and including the Barotse Floodplain in Zambia (Tweddle et al., 2004), and the Chobe and Kwando rivers, in the area of the Eastern Caprivi, Namibia.

Size

2.5cm (1ins)

Temp.

22-25°c (71-77°f.)

p.H.

6.5-7.2.

Characteristics

Dorsal spines (total): 2; Dorsal soft rays (total): 4-5; Anal spines: 0; Anal soft rays: 9 - 12; Vertebrae: 36 - 38. This species is generally more pallid and less conspicuously marked than other species of Zaireichthys. It differs from Zaireichthys conspicuus, Z. kunenensis, Z. lacustris and Z. maravensis in possessing a narrow premaxillary tooth patch, less than 40% of the mouth width; from Z. monomotapa by the smaller number of rays in the dorsal fin, 4-5 soft rays vs. 5-6), pectoral fins, 5-7 vs. 7-8, and caudal fin, 9-13 vs. 14-16; from Z. kavangoensis in colour pattern.

Colouration

In life it is almost transparent, preserved and usually very pale yellow, with a few minute black spots scattered irregularly over the body. A few specimens are darker, but rarely show a definite pattern except for a series of darker patches along the back, the first at the base of the dorsal, and an irregular darker line mid-laterally. The dark individuals can be readily distinguished from the other members of the genus by the shape of the melanophores, which are unusually large and rectangular in shape.

Aquarium Care & Compatibility

Found in shallow water with a sandy bottom where it buries itself. A sandy substrate in the Aquarium with boulders and rocks alternated with these sandy areas would suffice. Smaller fish such as Tetras etc. can be added as tankmates.

Reproduction

Not recorded but may practice brood care (Seegers, L., 2008).

Sexual differences

Not recorded

Diet

It feeds on small invertebrates, including mayfly nymphs and caddis fly larvae. Small live foods should be added to their diet.

Glossary of Terms

Anal fin: The median, unpaired, ventrally located fin that lies behind the anus, usually on the posterior half of the fish.
Adipose fin: Fleshy finlike projection without rays, behind the rayed dorsal fin.
Caudal fin: The tail.
Dorsal fin: The primary rayed fin(s) on top of the body.
Pectoral fin: The paired fins just behind the head.
Vertebrae: The bones of the axial skeleton; divided into two sections, precaudal and caudal vertebrae.

Etymology

Zaireichthys: A fish from Zaire.
pallidus: Named for its very pale colouration.

References

Eccles, D.H., D. Tweddle and P.H. Skelton, 2011. Eight new species in the dwarf catfish genus Zaireichthys (Siluriformes: Amphiliidae). Smithiana Bull. (13):3-28.
Pedro Bragança, Jouke Van Der Zee, Phillip S Lobel, Ulrich Schliewen. Osteology and redescription of the miniature lampeye species of Congopanchax Poll, 1971 with an overview of miniature African freshwater fishes (Teleostei, Cyprinodontiformes, Procatopodidae). Spixiana 46(1):91-118.
Seegers, L., 2008. The catfishes of Africa: A handbook for identification and maintenance. Aqualog Verlag A.C.S. GmbH, Germany. 604 p.

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ScotCat Sources

Etymology-genus

Etymology-specific name

Other Sources

Fishbase

Catalog of Fishes

GBIF

FishNet2

iNaturalist