Notas experimentales sobre <i>Gambusia cf. affinis</i> (Osteichthyes: poeciliidae) en Argentina

Abstract

G. affinis is a native poecilid of North America. It was introduced in Argentina in 1945, since then G. affinis has established as stable populations in several provinces like Cordoba and Buenos Aires up to 35º S approximately. On this work, three different kinds of experiences have been made to obtain some ecophysiological features of this exotic fish. The results were compared with those of Cnesterodon decemmaculatus, a native poecilid widely used in bioassays in Argentina. Some comments were made upon the morphological and pigmentation aspects of both species. The incipient lethal level of pH (96 h) was estimated at 10.3. The average swimming capacity using the Fatigue Time technique with a constant velocity of 6.8 cm.s-1 was 46.6 min and the lethal temperature obtained by means of the Critical Maximum technique was 41.21 ºC. All the analyzed parameters were larger than those noted for C. decemmaculatus. Both species showed a significant loss in their pigmentation when they were exposed to light or high temperatures. However, there are not any references of presence for G. cf. affinis in Patagonia nor in Pampasian lagunas, it has shown to be more eurithopic than C. decemmaculatus suggesting that it fulfills all the requirements to be found in these regions together with other Cyprinodontiforms.