Gambusia alvarezi, the Yellowfin Gambusia from San Gregorio, Mexico

Abstract:

" This article profiles the Yellowfin Gambusia, Gambusia alvarezi, a brilliantly colored livebearer endemic to a single spring and short outflow in Chihuahua, Mexico. It introduces the species’ restricted distribution and vegetated, clear-water habitat, then outlines natural history—surface-oriented foraging, pronounced sexual dimorphism, and distinctive male color forms—without. The author shares practical guidance for aquarium care, emphasizing stable, well-oxygenated conditions, robust feeding, and planting, alongside notes on reproduction and colony management. A concise taxonomy section traces the species’ description, subsequent debates over its status, and current recognition. The piece closes with a conservation appeal, stressing the fragility of its tiny habitat and the need for attentive stewardship. "