Petrocephalus catostoma, a mormyrid
found in Lake Malawi; illustration from Skelton (1993), used by permission
of P.H. Skelton
Petrocephalus catostoma is a small (13 cm or 5 inch SL) mormyrid, known at Nkhota Kota, Malawi, as "Ntachi" and called the "Churchill" by European southern Africans. It is widespread in central and southern Africa. In his checklist of the fishes of Nyasaland (Malawi), Jackson (1961) regarded it as "not uncommon in pools and streams but not from the main lake." It has since, however, been collected along the lakeshore proper. FishBase includes Lake Malawi in the distribution summary, and lists two lakeshore localities in Mozambique on the occurrences page for this species: "4 km nord de la baie de Nego, lac Nyassa" and "Punta Messuli, lac Nyassa."

Skelton (1993) provides a brief summary of the ecology of this species on floodplains and in the more slowly flowing parts of rivers, where it congregates in shoals. The diet consists of small invertebrates including insect larvae. Breeding occurs during the rainy season; the fishes are suspected of moving upstream to breed. Skelton remarks, "An unconfirmed report claims the males are territorial and build a nest."

Petrocephalus catostoma is most similar to Pollimyrus castelnaui in the Lake Malawi fauna. However, P. catostoma is the only mormyrid found in Lake Malawi that has all of the following characteristics (adapted from Skelton, 1993: 92-93):

  1. Length of dorsal fin base slightly shorter than anal fin base;
  2. Chin without a swelling;
  3. Mouth small and inferior (located below and behind front of head); and
  4. Anterior and posterior nares (nostrils) on each side of head are close together, separated by less than the diameter of each.

The above painting by Dave Voorvelt is copyright © by the South African Institute for Aquatic Biodiversity (formerly known as the J.L.B. Smith Institute of Ichthyology). It is reproduced here from Skelton (1993) with the kind permission of Prof. P.H. Skelton.

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The Cichlid Fishes of Lake Malawi, Africa:

Last Update: 13 October 2000
Web Author: M. K. Oliver, Ph.D.
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