Poeciliidae, Bonaparte, 1831

Freyhof, Jörg, Yoğurtçuoğlu, Baran, Jouladeh-Roudbar, Arash & Kaya, Cüneyt, 2025, Handbook of Freshwater Fishes of West Asia, GmbH, Berlin / Boston: De Gruyter : 763

Family Poeciliidae

Livebearers

A large family of small, fresh- and brackish-water fishes distributed across the Americas, from southern USA to Argentina. The majority of species exhibit internal fertilisation and give birth to live young. They also exhibit striking sexual dimorphism, with females being larger and deeper-bodied than males. The male’s anal is modified into an intromittent organ (gonopodium) ( Fig. 65 ) through which sperm is introduced into the female’s body. Females store sperm, which can be used to fertilise several successive broods. The eyes of the embryos are occasionally visible in a blackish blotch through the female’s belly, immediately in front of and above the anal. One species, guppy Poecilia reticulata , is one of the world’s most popular aquarium fishes and has been released throughout the tropics and in various kinds of warm-water habitats elsewhere. Guppies and mosquitofish Gambusia holbrooki are typically introduced to control mosquito populations. However, global studies have demonstrated that these introductions have had only limited effects on mosquito numbers, with potentially negative or neutral impacts on native fish populations. There needs to be a clear justification for these introduction programs, which are ongoing in some countries. It has been demonstrated that mosquitofish is the main or one of the main causes of the critical decline or extirpation of several populations of species of Aphaniids and other fishes.

In West Asia, only Gambusia holbrooki is widespread. In addition to the species discussed here, other introduced poecilids may be present, particularly in and around cities. Specialist aquarium literature will allow theiridentification.

Further reading. Meyer et al. 1985; Meffe & Snelson 1989; Miller 2005; Freyhof et al. 2020 (introductions in Arabia).

Key to species of Poeciliidae in West Asia

1a - Male with long, sword-like prolongation of lower caudal, both sexes with a prominent, red, black, or green midlateral stripe. ……………… Xiphophorus hellerii

1b - Male without prolongation of caudal, without prominent midlateral stripe. ………………2

2a - Pelvic of male unmodified, tip of first ray not enlarged, similar in male and female in size and shape;gonopodium long. ……………… Gambusia holbrooki

2b - Pelvic of male modified, tip of first ray enlarged, different in male and female; gonopodium short. ………………3

3a - Body very short and deep; dorsal in male and female equal; flank often red, similar colour in both sexes. ……………… Xiphophorus maculatus

3b - Body moderately elongate, without grey blotch on posterior part of caudal peduncle; dorsal larger in male than in female; flank not red, if with red blotches, then in male only. ………………4

4a - Dorsal and caudal in male with blue, white, or red colour; flank in male with a variable colour pattern of red, turquoise, yellow, and black blotches and short stripes. ……………… Poecilia reticulata

4b - Both sexes with rows of small black, grey, or brown spots on flank or flank black or black mottled; male without coloured blotches or stripes. ………………5

5a - Dorsal origin above or in front of anal origin; 12–16½ dorsal rays in male forming a large sail. ……………… Poecilia “ latipinna ”

5b - Dorsal origin behind vertical of pelvic origin in male; usually 9½ dorsal rays in male, rays slightly prolonged. ……………… Poecilia “ shenops ”

Figures

Figure 65: Schematised poecilid showing sexual dimorphism in anal fin shape of male (left, a) and female (right, b), and modified anal rays of male (gonopodium, c) (from Kottelat & Freyhof 2007, c, after Berg 1949b).