Following Loiselle (2006) it is diagnosed as follows: maxilla relatively immobile, bound at its posterior end to the preorbital by a fold of skin; premaxillary ascending processes flat and broad, tapered posteriorly and not overlapping in the midline; presence of a single pair of tubular nares; refelective pineal spot absent; squamation in anterior portion of body of the ‘E-type’ (sensu Hoedemann, 1958) with prominent ‘H-type’ scales; lateral line not present although some large specimens possess a shallow pit in the centre of some scales; papillae on scales and fin rays absent; haemal arches not expanded and haemal spines without pleural ribs; in adults hypural plates fused to form a hypural fan, with the join lines visible in juveniles; caudal-fin rounded to truncate with the central rays never extended; basal third to three-quarters of caudal-fin heavily-scaled, the scales in straight rows one scale wide, each series on the interspace between two rays; caudal-fin without a median lobe; filamentous extensions of the dorsal and caudal-fins variably present in males; dark gular bar variably present; no cross bars on the body; no dark spot at base of caudal-fin in males, variably present in females.

Molecular analysis suggests this genus represents the least evolved killifish known from which a large percentage of killifish are derived from.

Unlike the true annual killifish, they live as long as similar fishes, a few years, 3 years is not uncommon 5 is unknown.

Discovered by Robert Playfair in the Seychelles in 1863 the species was described as Haplocheilus playfairi by Gunter in 1866 and were moved to Pachypanchax by Myers in 1933; first kept in aquaria in France in 1867 (but not successfully, they died without reproducing) from a collection by Edward Wright.


PACH:PLA:Zanzibar population

A population of P. Playfairi was moved from The Seychelles to Zanzibar by zoologist Dr. Walter Aders after WWI for mosquito control as a public health initiative where they survived for decades even after being abandoned and at least until after WWII. Subsequently eaten by invasive Tilapia when checked by Wildekamp et al in 1997 and Nagy in 2008 they are considered extinct on Zanzibar Island now although this population remains in the aquarium hobby, as these were one of the first tropical fish and the first killifish held in the earliest days of the aquarium hobby.

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Catalog of Fishes
playfairii, Haplochilus Günther [A.] 1866:314 [Catalogue of the fishes in the British Museum v. 6; ref. 1983] Seychelles. Syntypes: BMNH 1864.11.15.91-93 (3 or 2), 1865.3.18.100-101 (2), 1866.1.19.40-43[or 70-73] (4), 1866.1.19.63-69 (7 or now 5), 1867.8.16.24-25 (2); MSNG 9297 (1); USNM 12611 (10); ZMB 6085 (2). Type catalog: Paepke & Seegers 1986:162 [ref. 19981]. •Valid as Pachypanchax playfairii (Günther 1866) -- (Parenti 1981:473 [ref. 7066], Wildekamp et al. 1986:275 [ref. 6198], Poll & Gosse 1995:211 [ref. 24781], Seegers 1997:16 [ref. 23895], Murphy & Collier 1997:797 [ref. 25585], Lazara 2001:245 [ref. 25711]). Current status: Valid as Pachypanchax playfairii (Günther 1866). Aplocheilidae. Distribution: Seychelles. Habitat: freshwater, brackish.

Further References

  1. Günther, A., 1866 - Catalogue of fishes in the British Museum v. 6: i-xv + 1-368
    Catalogue of fishes in the British Museum. Catalogue of the Physostomi, containing the families Salmonidae, Percopsidae, Galaxidae, Mormyridae, Gymnarchidae, Esocidae, Umbridae, Scombresocidae, Cyprinodontidae, in the collection of the British Museum.
  2. Hertwig, S. T., 2008 - Zoologica Scripta 37(2): 141-174
    Phylogeny of the Cyprinodontiformes (Teleostei, Atherinomorpha): the contribution of cranial soft tissue characters.
  3. Loiselle, P. V., 2006 - Zootaxa 1366: 1-44
    A review of the Malagasy Pachypanchax (Teleostei: Cyprinodontiformes, Aplocheilidae), with descriptions of four new species.
  4. Murphy, W. J. and G. E. Collier, 1997 - Molecular Biology and Evolution 14(8): 790-799
    A molecular phylogeny for aplocheiloid fishes (Atherinomorpha, Cyprinodontiformes): the role of vicariance and the origins of annualism.
  5. Myers, G. S., 1933 - American Museum Novitates No. 592: 1 p.
    Pachypanchax, a New Genus of Cyprinodont Fishes from The Seychelles Islands and Madagascar.

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Richard J. Sexton