Capacidad de natación en <i>Gymnogeophagus meridionalis</i> (Pisces, cichlidae)

Abstract

The cichlidae are recognized as maneauver specialists characterized by low crusing speeds and some acceleration capacity. In this work the swimming capacity of Gymnogeophagus meridionalis and the relation it has with some morphometric variables were experimentally evaluated under laboratory conditions and compared with others cichlid species. Using a flow chamber where the water flowed at a constant velocity of 6.8 cm.s-1, fatigue times (TA) between 84 and 853 min were obtained for 10 specimens between 22.9 and 70.0 mm of standard length (Lst). The maximum swimming speed was estimated in 5.5 Lst.s-1 and the cruising speed was approximately 2.0 Lst.s-1. Comparatively, G. meridionalis’ average fatigue time (376.1 min) was longer than that mentioned for C. facetum (169.1 min) and shorter than preliminary data of Crenicichla sp. These differences are related to the corporal morphology. Whereas Crenicichla sp. presented the most elongated body shape with an average body height as a percent of Lst (AC%) about 22%; inside the orbicular cichlids group, G. meridionalis and C. facetum presented AC% of 43.2 y 47.5% respectively. The differences in swimming capacity between Gymnogeophagus meridionalis and C. facetum, both maneuver specialists, could be owed to a smaller body height and a narrow caudal peduncle.