Yucatán Gambusia, Gambusia yucatana
Yucatán Gambusia, Gambusia yucatana. Fish caught out of a freshwater pond at the Vidanta Grand Luxxe Resort, Playa del Carmen, Quintana Roo, February 2016. Length: 5.1 cm (2.0 inches). Catch, identification, and photo courtesy of George Brinkman, Guelph, Ontario, Canada.
The Yucatán Gambusia, Gambusia yucatana, is a member of the Livebearer or Poeciliidae Family, that is also known as the Mosquito Fish and Topminnow, and in Mexico as guayacón yucateco. Globally, there are forty-two species in the genus Gambusia, of which three are found in Mexican waters, two 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 Yucatán Gambusia has a moderately robust body that are somewhat compressed at the rear. They are light olive with large dark brown spots scattered in several rows on their sides. They have a dark bar under their eyes that does not extend into the gill cover. Their dorsal fin has 1 dominant row of dark spots with fainter rows of spots also present. Males have bright orange caudal fins with 2 or 3 rows of dark spots. Their head is robust and depressed with a small terminal slightly oblique mouth. They have a projecting lower jaw that opens at the front and is equipped with an outer row of large backward curved teeth and several rows of small pointed teeth. Their anal fin has 10 or 11 rays and originates before the dorsal fin; their caudal fin is rounded; their dorsal fin has 7 to 10 rays is located near the rear of the body and has a short base; their pectoral fins are high on the body and originate in front of the pelvic fins; and the pelvic fin tips are swollen in females. Their body is covered with large smooth scales.
The Yucatán Gambusia is a shallow freshwater species found at times in brackish waters of coastal lagoons at depths up to 1 m (3 feet). Females reach a maximum of 8.0 cm (3.1 inches) in length and males 5.5 cm (2.2 inches). They spend the majority of their time on the water surface with their lower jaw projecting forward and upward allowing them to “gulp” air and skim microscopic matter from the water surface. In turn they are preyed upon by numerous birds and fish including needlefish. Reproduction is viviparous with young born live. The Yucatán Gambusia is poorly studied with very limited information available about their lifestyle and behavioral patterns including specific details on age, growth, longevity, movement patterns, diet, habitat use, and reproduction.
In Mexico waters the Yucatán Gambusia has a limited distribution being found only in the freshwater drainage systems of the Yucatán Peninsula that feed into the Atlantic Ocean.
The Yucatán Gambusia is most likely confused with the Caribbean Gambusia, Gambusia puncticulata (dark stripe under eyes) and the Pike Killifish, Telonesox belizanus (extended pointed snout; prominent spot at base of caudal fin).
From a conservation perspective the Yucatán Gambusia has not been formally evaluated. They are utilized as a component of an expanded effort to utilize Gambusias to control mosquitoes as they eat mosquito larvae. They are currently being breed in Acapulco, Guerrero, and along the Pacific Coast with fish handed out to families for use in their rainwater collection barrels, buckets, and tubs where water is stored. As such they have become invasive in some areas. They are also used extensively by the aquarium trade.