Half-Black Blue Guppy
Poecilia reticulata
About this strain
The Half-Black Blue splits the fish cleanly: the rear half of the body is solid black or very dark, while the forward half is lighter, with the tail displaying a rich blue — ideally matching the show standard of a deep, uniform blue caudal fin. The black body portion should be dense and not fade toward the mid-body. The clean two-toned body silhouette is what distinguishes HB strains from Tuxedos, which have a softer boundary. HB Blues are a classic show strain and remain highly competitive. Poor-quality specimens often show incomplete black coverage or pale, inconsistent tail color.
Origin
Half-Black strains have been selectively bred since at least the 1950s–60s by European and American hobbyists. The HB Blue is one of the oldest recognized competitive show categories.