Stippled Gambusia, Gambusia sexradiata

Stippled Gambusia, Gambusia sexradiata. Fish caught from a coastal steam in Belize, March 2022. Length: 4.7 cm (1.9 inches). Catch, photograph and Identification courtesy of Vince Golder, Santa Cruz, California.

The Stippled Gambusia, Gambusia sexradiata, is a member of the Livebearer or Poeciliidae Family, that is also known as the Stippled Mosquitofish and Teardrop Mosquito Fish and in Mexico as guayacón del sureste. Globally, there are forty-two species in the Gambusia Genus, of which four are found in Mexican waters, three in the freshwater systems that feed into the Atlantic Ocean and one species found in the freshwater systems of both the Atlantic and the Pacific Oceans.

The Stippled Gambusia has an elongated somewhat compressed body. They have a small slightly oblique mouth that opens at the front. They are stippled or mottled pattern and vary from brown to olive in color with irregular dark blotches or spots. They are adorned with beautiful stippling or speckling patterns that serve as excellent camouflage. They adult females can be distinguished by a gravid spot indicating the presence of developing young. They have a dark bar extending downward from the eye. Their anal fin is dark in color, elongated, and originates before the dorsal fin; the caudal fin is rounded and transparent with rows of prominent spots, the dorsal fin has short base and found well back in the body, and, the pelvic fins originate behind the pectoral fins. They are covered with large scales.

The Stippled Gambusia is a shallow freshwater species found at times in brackish waters of coastal lagoons, near shore where vegetation is present, with water temperature between 22°C (72°F) to 26°C (81°F) at depths up to 1 m (3 feet). They thrive in marshes, calm ponds and flowing streams. They are small in stature reaching a maximum of 3.8 cm (1.5 inches) in length with the females being bigger than the males. They are a schooling species that make rapid movements. They feed mainly on benthic, vegetation-associated invertebrates, and on terrestrial shoreline organisms. In turn they are preyed upon by numerous birds and fish. The Stippled Gambusia is a live-bearing fish with fish reaching sexual maturity in four months and a 28-day gestation period with each female giving birth to between 10 and 35 young.

In Mexican waters the Stippled Gambusia is found in freshewater systems from the Rio Nautla in northern Veracruz, along the Atlantic slope of Campeche, Oaxaca, Chiapas and Quintana Roo, south to Belize.

The Stippled Gambusia is most likely confused with the Caribbean Gambusia, Gambusia puncticulata (lack dark dark stripe under eyes), the Western Mosquitofish, Gambusia affinis (lacks prominent anal and dorsal fin spotting) and the Yucatán Gambusia, Gambusia yucatana (lacks tail spotting).

From a conservation perspective the Stippled Gambusia is currently considered to be of Least Concern with a wide distribution with declining populations in some regions attributed to habitat loss and degradation. They are considered to be important in maintaining the ecological balance of their habitats and for controlling mosquito populations. They are also used extensively by the aquarium trade due to lively nature, adaptive behaviors vivid colors.

s #310 Stippled Gambusia (Gambusia sexradiata)