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This profile reviews the taxonomy, identification, distribution, habitat, biology, and aquarium care of Xiphophorus nezahualcoyotl, a northern swordtail endemic to northeastern Mexico. It summarizes the species’ historical recognition, distinctive morphology, and occurrence across river, spring, and pool habitats within the Río Pánuco and Río Tamesí regions. The account also discusses sexual dimorphism, courtship, mating behavior, livebearing reproduction, and social interactions, along with practical information on maintenance and breeding in captivity. Particular attention is given to the species’ complex evolutionary history, including conflicting genetic signals and evidence of past hybridization, while also considering its conservation status and remaining gaps in knowledge of its natural ecology.

Subscribers can now upload a fish photograph and compare it with the determined photographs in the FFM collection. more