Overview

Comprehensive Description

General Description

Petrocephalus balayi, described by Sauvage (1883), is a large, robust species within the genus Petrocephalus (maximum standard length = 95.6 mm SL). Body ovoid, body 2.5–2.8 longer than high and laterally compressed. Head length between 3.3 and 3.4 times (holotype = 3.3) in standard length. Head width 1.9 times (holotype = 2.2) in head length. Snout short, wide and square–shaped. Mouth wide (2.7 ≤ Head length/Mouth width ≤ 3.1, holotype = 3.4), sub–terminal, opening under the anterior half of the eye. Teeth small and bicuspid, 30 in a single row in the lower jaw and 20–21 in the upper jaw. Eye small (4.5 ≤ Head length/Eye diameter ≤ 4.8, holotype = 4.6). Dorsal and anal fins originate in the posterior half of the body (standard length/pre–dorsal distance = 1.6 and standard length/pre–anal distance = 1.6), with pre–dorsal distance equal to pre–anal distance. Pre–dorsal distance slightly exceeds pre–anal distance in the holotype. Dorsal fin with 22 branched rays (holotype = 21). Anal fin with 27 branched rays (holotype = 26). Scales cover the entire body, except for the head. Lateral line visible and complete with 36 pored scales. Caudal peduncle relatively thick (1.7 ≤ CPL/CPD ≤ 1.8, holotype = 2.3). Twelve circumpeduncular scales. Skin on head thick, becoming opaque with formalin fixation. Knollenorgans organized into the three rosettes.

Body gray/silver, slightly darker dorsally. The head is also slightly darker than the rest of the body. Iridescent pigment along side of body sometimes visible with correct orientation of light. Pigmentation pattern with three black patches: (1) a distinct round black mark on each side of the body below the dorsal fin origin; (2) an ovoid black mark on each side at the base of the caudal peduncle that does not extend onto the upper and lower parts of the caudal fin; (3) a black mark, sometimes diffuse in larger individuals but always present, at the base of the pectoral fins. The fins themselves are translucent.

Creative Commons Attribution Non Commercial Share Alike 3.0 (CC BY-NC-SA 3.0)

© Lavoué, Sébastien

Source: Africhthy

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Distribution

Range Description

Petrocephalus balayi is known from the Central Congo River basin. It has also been recorded from Kindu, Lualaba system. It is not known from the Lukénie, Kasai and Kwango systems. It also occurs in the Lower Guinea region where it occurs in the lower course of the Ogowe River (Gabon) in numerous associated lakes, and in the small coastal rivers from south of the Ogowe to the border between Gabon and Congo.
Creative Commons Attribution Non Commercial Share Alike 3.0 (CC BY-NC-SA 3.0)

© International Union for Conservation of Nature and Natural Resources

Source: IUCN

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Africa: Congo River basin and Ogowe River in Gabon (Ref. 3203, 85311).
  • Gosse, J.-P. 1984 Mormyridae. p. 63-122. In J. Daget, J.-P. Gosse and D.F.E. Thys van den Audenaerde (eds.) Check-list of the freshwater fishes of Africa (CLOFFA). ORSTOM, Paris and MRAC, Tervuren. Vol. 1. (Ref. 3203)
Creative Commons Attribution Non Commercial 3.0 (CC BY-NC 3.0)

© FishBase

Source: FishBase

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Petrocephalus balayi occurs in the southern part of the Lower Guinea province (from the Ogooué River) and in the Congo River basin, including Odzala National Park and the Lower Congo River

Creative Commons Attribution Non Commercial Share Alike 3.0 (CC BY-NC-SA 3.0)

© Lavoué, Sébastien

Source: Africhthy

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

West-central Africa.
Creative Commons Attribution Non Commercial Share Alike 3.0 (CC BY-NC-SA 3.0)

© FishWise Professional

Source: FishWise Professional

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Physical Description

Size

Max. size

11.0 cm TL (male/unsexed; (Ref. 42522))
Creative Commons Attribution Non Commercial 3.0 (CC BY-NC 3.0)

© FishBase

Source: FishBase

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

to 95.6mm SL

Creative Commons Attribution Non Commercial Share Alike 3.0 (CC BY-NC-SA 3.0)

© Lavoué, Sébastien

Source: Africhthy

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Diagnostic Description

Petrocephalus balayi is distinguished from all other Petrocephalus species in Central Africa by the following combination of characteristics: dorsal fin with 20-22 branched rays, anal fin with 26 or 27 branched rays, eye small (HL/ED=4,5-4,9), mouth very wide, associated with a very characteristic head shape when viewed from below, 14 teeth or more in the upper jaw, 28 teeth or more in the lower jaw (Ref. 85331). Melanin pattern consisting of the following: (1) a distinct black round mark on each side of the body below dorsal fin origin; (2) an ovoid mark on each side at the base of the caudal peduncle, not extending onto the upper and lower parts of the caudal fin; (3) a black mark, sometimes diffuse but always present, at the base of the pectoral fins (Ref. 85331).
Creative Commons Attribution Non Commercial 3.0 (CC BY-NC 3.0)

© FishBase

Source: FishBase

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Petrocephalus balayi is distinguished from all other Petrocephalus species in Central Africa by the following combination of characteristics. Dorsal fin with 20–22 branched rays. Anal fin with 26–27 branched rays. Eye small (4.5 ≤ Head length/eye diameter, range = 4.5–4.9). Mouth very wide (Head length/mouth width ≤ 3.9, range = 2.7–3.9) associated with a very characteristic head shape when viewed from below. Fourteen teeth or more in the upper jaw (range = 14–21). Twenty–eight teeth or more in the lower jaw (range = 28–38). Melanin pattern consisting of the following: (1) a distinct black round mark on each side of the body below dorsal fin origin; (2) an ovoid mark on each side at the base of the caudal peduncle, not extending onto the upper and lower parts of the caudal fin; (3) a black mark, sometimes diffuse but always present, at the base of the pectoral fins. The EOD is of normal polarity.

Creative Commons Attribution Non Commercial Share Alike 3.0 (CC BY-NC-SA 3.0)

© Lavoué, Sébastien

Source: Africhthy

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Ecology

Habitat

Habitat and Ecology

Habitat and Ecology
This is a demersal species.

Systems
  • Freshwater
Creative Commons Attribution Non Commercial Share Alike 3.0 (CC BY-NC-SA 3.0)

© International Union for Conservation of Nature and Natural Resources

Source: IUCN

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Environment

demersal; freshwater
Creative Commons Attribution Non Commercial 3.0 (CC BY-NC 3.0)

© FishBase

Source: FishBase

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

General Ecology

Ecology

In Odzala, Petrocephalus balayi seems to prefer the small tributary creeks flowing through forest. In Gabon (Lower Guinea province), Petrocephalus balayi occurs in the lower courses of the Ogooué River and numerous associated lakes (and their tributary streams), as well as in small coastal creeks from south of the Ogooué to the border with the Congo.

Creative Commons Attribution Non Commercial Share Alike 3.0 (CC BY-NC-SA 3.0)

© Lavoué, Sébastien

Source: Africhthy

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Life History and Behavior

Behavior

Electric Organ Discharge

EOD recordings are only available for a small number of individuals: one specimen from the coastal river Doumvou at Doumvou, Gabon (Lavoué, et al., 2004); and two specimens from Odzala National Park, Republic of Congo (Lavoué, et al., 2008). Among these few recordings, the overall waveform of EODs produced by P. balayi seems to be typical for the genus, similar to those produced by several other Petrocephalus species (mainly biphasic). EOD duration = 0.324 – 0.340 msec.

Electrocytes in P. balayi are of type NPp.

Creative Commons Attribution Non Commercial Share Alike 3.0 (CC BY-NC-SA 3.0)

© Lavoué, Sébastien

Source: Africhthy

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Evolution and Systematics

Evolution

Phylogenetic Relationships

Petrocephalus balayi forms a monophyletic group with Petrocephalus odzalaensis and Petrocephalus binotatus.

Creative Commons Attribution Non Commercial Share Alike 3.0 (CC BY-NC-SA 3.0)

© Lavoué, Sébastien

Source: Africhthy

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Conservation

Conservation Status

IUCN Red List Assessment


Red List Category
LC
Least Concern

Red List Criteria

Version
3.1

Year Assessed
2010

Assessor/s
Moelants, T.

Reviewer/s
Brummett, R., Mbe Tawe, A.N., Dening Touokong, C., Reid, G.M., Snoeks, J. Staissny, M., Moelants, T., Mamonekene, V., Ndodet, B., Ifuta, S.N.B., Chilala, A., Monsembula, R., Ibala Zamba, A., Opoye Itoua, O., Pouomogne, V., Darwall, W. & Smith, K.

Contributor/s

Justification
The species is widespread without major threats throughout central Africa and is assessed as Least Concern.
Creative Commons Attribution Non Commercial Share Alike 3.0 (CC BY-NC-SA 3.0)

© International Union for Conservation of Nature and Natural Resources

Source: IUCN

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Population

Population
No information available.

Population Trend
Unknown
Creative Commons Attribution Non Commercial Share Alike 3.0 (CC BY-NC-SA 3.0)

© International Union for Conservation of Nature and Natural Resources

Source: IUCN

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Threats

Major Threats
None known.
Creative Commons Attribution Non Commercial Share Alike 3.0 (CC BY-NC-SA 3.0)

© International Union for Conservation of Nature and Natural Resources

Source: IUCN

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Least Concern (LC)
  • IUCN 2006 2006 IUCN red list of threatened species. www.iucnredlist.org. Downloaded July 2006.
Creative Commons Attribution Non Commercial 3.0 (CC BY-NC 3.0)

© FishBase

Source: FishBase

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Management

Conservation Actions

Conservation Actions
None known.
Creative Commons Attribution Non Commercial Share Alike 3.0 (CC BY-NC-SA 3.0)

© International Union for Conservation of Nature and Natural Resources

Source: IUCN

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Disclaimer

EOL content is automatically assembled from many different content providers. As a result, from time to time you may find pages on EOL that are confusing.

To request an improvement, please leave a comment on the page. Thank you!