Eastern mosquitofish
Gambusia holbrooki
The maximum size of females is about 5 cm, being the males smaller. The head is broad and flattened, with big eyes. The mouth is in a superior position. The color of the body gray-green. The dorsal and caudal fins have black dots. Mature females have a black spot on the abdomen.
It is a species native to North America. It was introduced at the beginning of the 20th century and is currently distributed throughout Catalonia.
It lives in all kinds of environments, from running waters to reservoirs, wetlands and coastal lagoons. Prefers shallow waters, with areas of vegetation. It has a certain resistance to pollution and high temperatures. Reproduction is viviparous, i.e., the embryos develop inside the female. The diet is made up of all kinds of invertebrates.
It is an extremely harmful invasive species for native species, especially the Iberian toothcarp and the samaruc.
Distribution
Mummichog
Fundulus heteroclitus
It is a fish that measures less than 10 cm. A characteristic that differentiates it from the Iberian toothcarp and the samaruc is that the dorsal fin originates in front of the anal. Males are greenish, with dark stripes on the flanks and some bright white and blue dots. Females are paler, no stripes on the sides.
The mummichog is of American origin, and was detected in Catalonia for the first time in 2005 in the Ebro delta, where it is currently expanding.
It is a species that adapts very well to changes in the salinity of estuaries and deltaic areas. It lives in shallow marshy waters, coastal lagoons, irrigation canals, etc. They lay their eggs on the aquatic vegetation, mainly filamentous algae. It feeds on invertebrates and plant matter.
The mummichog is a great threat to the Iberian toothcarp, as it can colonize areas of high salinity where the Iberian toothcarp had its main refuges against pressure from the mosquitofish.
Distribution
