Tuxedo Swordtail Swordtail
Xiphophorus hellerii
About this strain
The rear half of the body — from roughly mid-flank back — is strongly darkened with black or dark gray pigmentation, while the front half retains the base body color (commonly red or orange), creating a two-tone 'tuxedo' split. On a well-bred male the division between light and dark zones is clean and sharp, not blurry or mottled. The sword is typically dark-edged. Tuxedo is a dominant genetic pattern that has been crossed into many color strains; you'll encounter red tuxedo, gold tuxedo, and others. Select for a clearly defined color boundary for the most dramatic effect.
Origin
The tuxedo pattern (also called 'half-black') is a melanophore expression trait refined in swordtails through selective breeding, drawing from similar work done with guppies and platies, established commercially by the late 20th century.