Etymology:
Gambusia: derived from the Cuban term Gambusino, which means “nothing”
marshi: named in honour of E. G. Marsh, Jr,
First description:
Minckley, W.L. 1962: Two new species of fishes of the genus Gambusia (Poeciliidae) from northeastern Mexico. Copeia 1962
Common name:
Robust gambusia
History:
Collected by Minckley, Craddock, Donald R. Tindall, and Charles B. Stone on 16 August 1960
Group:
Panuco species group comprising of G. marshi, G. Panuco, G. regain,
Type Locality:
Río Salado de los Nadadores, near junction with Río Salado de Monclova, 1mile south of
Hermanas, Coahuila, Mexico
Distribution:
Cuatro Cienegas basin and the Río Salado drainage, Coahuila, Mexico
Habitat:
Gambusia marshi is generally found in slow moving waters, regarded as most adaptable fish that can live in most environments, it can be found in most types of habitat from natural streams, marshes and lakes to artificial canals.
Size:
Males 3.5cm, Females 6cm
Distinguishing Characteristics:
Gambusia marshi has a narrow but deep body, this is more noticeable in the male than the female who does have a higher back. This species has a relatively large head with a superior mouth. The dorsal fin is positioned quite far back on the body and the anal fin is large and rounded.
Colour/Pattern Variability:
A base colour of yellowish brown with a dark brown lateral strip, the belly is white with a blue tint. It is not uncommon to find some specimens have black spots on their back.
The dorsal fins of adult males is almost orange and all other fins are yellow, females show little colour in their fins.
Behaviour:
This is an active, but peaceful fish
Husbandry:
This species can be kept in most environments, but does seem to do better in a planted tank with a gentle flow. An omnivore in nature that prefers diet of live food
Breeding Notes:
Generally not a problem to breed, ensure plenty of places for the fry to hide or use nursery tanks. Females will drop fry after about 28 days and depending on the size of the female, you can expect anything from 10 to 40+ fry.