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Library > Cichlids > General Articles > Taxonomy of Cichlids >Sub Family Ptychochrominae > Genera Ptychochromis >Ptychochromis onilahy

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Species Ptychochromis onilahy  
Scientific classification
Image Credit : Ian Heart
Kingdom : Animalia
Phylum : Chordata
Class : Actinopterygii
Order : Perciformes
Suborder : Labroidei
Family : Cichlidae
Sub Family : Ptychochrominae
Genus : Ptychochromis
Morphometric Data
Total Length (inches)
Standard Length (inches) 3.10
Measurements as a % of Standard Length
Fork _length
Pre_ anal _length
Pre dorsal_length
Pre_ pelvic_length
Body_ depth
Eye diameter (HL)
Pre_orbital_length (HL)
Snout_ length
Inter orbital_width (HL)
Pre orbital_depth (HL)
Caudal _peduncle_depth
Caudal _peduncle_length
Pectoral _fin_length
Pelvic_ fin_length
Length _of_last_ dorsal_ fin_spine
Scientific Name : Ptychochromis onilahy
Common Name :
Geo Origin : AFRICA, Other African, Africa: Madagascar.
Conservation Status : Extinct
Diet :
Gender Differences :
Breeding :
Temperament :
Con specific Temperament :
Standard Length : 3.1 "
Total Length :
Water Hardness:
Difficulty :


Ptychochromis onilahy is a medium sized fish which has never been seen since its initial description in 1962.

It was initially found in Onilahy river in southwestern Madagascar and has not been sighted since.

However the Onilahy river system is large and there might be small isolated populations.

(Click for details of Cichlid taxonomy)

(Click for details of genus article)

Ptychochromis onilahy was first described by Stiassny & Sparks , in 2006.

The genus Ptychochromis was described by Steindachner in 1880.

The species name Onilahy is derived from Onilahy river system, the only known sighting of this fish.

(Click for description of fish body parts)

Ptychochromis onilahy reaches a length of about 5.1 " (SL).

Body is deep and laterally compressed.

Lateral snout outline is straight.

Predorsal head profile is convex from middle of eye to dorsal-fin origin.

Dorsal body profile from dorsal-fin origin is smoothly convex.

Ventral(lower) body profile is more or less straight.

Caudal peduncle is short, deep, and laterally compressed.

Dorsal-fin origin is located anterior to vertical through pectoral-fin insertion.

Pelvic-fin origin is located well posterior to vertical through pectoral-fin insertion.

Total vertebral count is 26 or 27, with 13 vertrebra located on body and 13-14 located on caudal region.

Lower and upper jaws are similar (isognathous).

Teeth in jaws are bilaterally symmetrical and bicuspid, with crowns some what expanded distally and slightly recurved.
Outer row teeth of both jaws are enlarged and graded in size laterally.

Like all cichlids, P. onilahy have pharyngeal teeth.
Upper and lower pharyngeal tooth plates are well developed with strong teeth.

Body is covered with large, regularly imbricate, weakly ctenoid scales from about level of midorbit to proximal portion of caudal fin.

Scales above upper lateral line to about level of origin of soft dorsal fin are cycloid.

Scales on flanks becoming increasingly ctenoid posteriorly, but at most only weakly so.

Scales on nape and head regionare cycloid.

There are four or five rows of cycloid scales on cheek.

Scales on opercle and subopercle missing in all specimens.

Anterior chest scales are reduced in size and embedded.

Scales on chest are weakly ctenoid, except anteriorly where they are cycloid.

Scales on belly are cycloid.

Snout, and region near eyes does not have any scales.

Scales on caudal fin reduced in size.

Lateral line has 33 or 34 scales.
There are five scales in diagonal from lateral line to dorsal-fin origin.

There are four or five scale rows between bases of pectoral and pelvic fins.
No scale rows present along dorsal- and anal-fin bases.

Dorsal fin is placed vertically above pectoral fin base, slightly anterior and has XII spines, 12 soft rays.

Anal fin has III spines and eight or nine soft rays. First anal spine is very short, second and third spines elongate and of similar length.

All fins in preserved specimens were damaged, making determination of original fin shape impossible.

Pelvic fins are short, and extend to origin of anal fin.


Coloration :-

According to Kiener( 1963) and Kiener and Mauge´ (1966), adults of this species were uniformly gray brown, paler ventrally and lacking any obvious body markings.

Geographical distribution

Ptychochromis onilahy was initially found in Onilahy river in southwestern Madagascar and has not been sighted since.

However the Onilahy river system is large and there might be small isolated populations.


Habitat :


Conservation Status :

IUCN lists this as an undescribed species with voucher specimens held at MNHN.

It has not been collected for many years despite targeted efforts within its former range.

Five preserved specimens represent the only known material collected from the Onilahy River in 1962.

The main impacts thought to have caused the decline of this species are deforestation leading to loss of habitat through increased sedimentation, competition from introduced tilapias and overfishing.

This species is assessed as Extinct.

Aquarium upkeep

There are no records of this species ever being kept in aquariums.



  Sandeep Raghuvanshi
Citations/Further Reading  

Froese, R. and D. Pauly. Editors:Fishbase, World Wide Web electronic, version (10/2013),2013, ISBN :

ITIS: Integrated Taxonomic Information System,,, ISBN :

John S. Sparks:A new and presumably extinct species of Ptychochromoides (Teleostei: Perciformes: Cichlidae) from central Madagascar. Perciformes: Cichlidae) from central Madagascar. Zootaxa 524, 1-15: 13-13,,2004,Zootaxa 524, 1-15: 13-13, ISBN :

Melanie L.J. Stassiny, John S. Sparks:Phylogeny and Taxonomic Revision of the Endemic Malagsy Genus Ptychochromis with the description of Five New species and a Diagnosis for Karia, New Genus,2006,American Muesum of Natural History ISBN :