Ptychochromis oligacanthus – by Jose M. Gonzalez

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Madagascar cichlids have been described as being living fossils giving rise to all cichlids from the new world.

Phylogenetic studies place their evolution 165 million years ago Chakrabarty)
even prior to the separation of Madagascar from Africa and more recently from the Indian continent.

The genus Ptychochromis was erected by Steindachner in 1880 and was well
represented throughout the northwest, southwest and eastern Madagascar (Sparks et al) until recent years.

Human activities, deforestation and exotic fish introductions have contributed to the disappearance of many local fish populations and species extinctions since the 1960’s.

For conservation biologists, all cichlids from the island are considered vulnerable and some species critically endangered.


Ptychochromis oligacanthus



Ptychochromis oligacanthus


The following text is based on my observations of this species to help guide the propagation and conservation of this small gem:

Ptychochromis oligacanthus is one of several species in the genus that has been described (I presume a few more will be described before they become extinct).

It is the smallest of the genus, with male adults reaching 6 inches in length.

There is sexual dimorphism with the male being typically larger (as large as twice the female size) and developing reddish to pink coloration of the caudal, dorsal and anal fins (thereby reference to “Northern red fin”).

The rest of the body is reminiscent of the genus Thorichthys from central and south America. The body has background grey coloration with many small shimmering specks.

Large black irregular blotches will cover the body with varying presentation depending on the mood of the fish.

There is however one dark blotch that is common only to oligacanthus alone on the upper part of the operculum and this is used to distinguish this fish from other member of the genus.

There is a variation in coloration with the brightest colors found in specimens from the island of Nosy Be in the northwest.




Ptychochromis oligacanthus may be found in crater lakes (Nosy Be) as well as lakes and rivers in the mainland but it is fairly restricted in the northwest.

This population is now documented to be a new species based on genetic markers according to Lovahaisoa and Ranalison.

It is characterized by more spangling and blue hues on the lips and along the body.




This fish is not demanding in regards to the water chemistry, though as with all cichlids, goodn aquarium maintenance will enhance the health of the fish.

Temperature, on the other hand, as with most other Madagascar cichlids is important- and should be maintained around 80F, higher during spawning up to 84F.

This fish is prone to bloat if fed a diet rich in protein, thus insect larvae low in fat and a diet containing plant matter is recommended (almost any commercial vegetarian food for fish is appropriate).

Sand is the preferred substrate as this fish will shift through it looking for food and clear sand over a flat rock to spawn.

The most important aspect of Malagasy cichlids is their lack of natural defenses against Ich. All cichlids from the island are extremely susceptible to Ich, members of the Paretroplus genus will die within 24 hr identification of the disease.

It’s highly advisable using extended quarantine periods for any new fish (I isolate fish at least 4 weeks).

Pty. oligacanthus along with Pe. polyactis are the most salt tolerant of Malagasy cichlids and may be found living in brackish water- this is an advantage when treating Ich along with raising water temperature and using formalin.




The temperament of the fish needs to be considered when choosing tankmates, in the wild they may be found living with members of Rheocles, Bedotia and Paretroplus.

This fish is fairly nonaggressive so fish of similar temperament may occupy the same tank, though this reduces the chance of watching them reproduce.

Consider only using Malagasy or Australian rainbows and killifish to encourage breeding.




Spawning behavior is quite interesting, a male may try to mate with more than one female and occasionally more than one female will lay eggs over the same surface.

The fish is rather skittish so carefully selected tank mates will lead to many successful spawns.

I will usually let the parents raise their offspring unless the eggs are eaten multiple times, then I look for anything stressing the fish (usually is a matter of too small a tank).

Fry will readily take newly hatched brine shrimp and finely crushed flake. The fry are rather small and may swim against the water surface if isolated from the parents so colored glass or green pond water will correct this odd behavior.



Remember that every thing about these fish is unique even for cichlids, because they have hardly evolved over many millions of years, providing a natural environment will lead to many hours of observing this unique fish.

Let me not forget that the fry are very slow to grow as is the case with most Malagasy cichlids.


For more information on this species and other Madagascan fish, visit the Madagascar Endangered fishes group on Facebook: HERE!!




Phylogeny and Taxonomic Revision of the Endemic Malagasy Genus Ptychochromis (Teleostei: Cichlidae), with the Description of Five New Species a Diagnosis for Katria, New Genus.

Melanie L. Stiassny and John S. Sparks American Museum Novitates September 8, 2006.

Number 3535

Systematics and historical biogeography of Greater Antillean Cichlidae. Prosanta Chakrabarty

Molecular Phylogenetics and Evolution. In press 2006

The Endemic Cichlids of Madagascar Patrick de Rham and Jean-Claude Nourissat

Phylogenetic, morphological and systematic studies of three genera of Cichlidae (Teleosts fish,

Perciformes) endemic of Madagascar. Lovahaisoa, Rakotomamonjy and Ranalison, Oliarinony.

Biodiversity Intenational Journal. Volume 2, issue 6, 2018 538-543





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