Jenynsia onca — Jaguar Onesided Livebearer — 0.5"–1"

Jenynsia onca is one of the most biologically unusual livebearers in the freshwater hobby. Commonly called the Jaguar Livebearer or Spotted Onesided Livebearer, this small South American fish carries a remarkable evolutionary quirk: males have a gonopodium permanently fixed to either the right or left side — and can only mate with females of the opposite orientation. It is a one-of-a-kind piece of living biology you will not find in any guppy or platy.

Like the Gymnogeophagus we also keep, Jenynsia onca is a temperate species that thrives in cooler water — making it an excellent companion fish or a standout species for a Uruguayan biotope setup.

Our stock was personally wild-caught from the Rio Yi in Uruguay — a tributary of the Rio Negro basin and prime Jenynsia habitat. These are F1 offspring bred directly from those wild-caught parents, offering genuine locality genetics from a documented collection site.

Current size: 0.5-1 inch. All fish are quarantined and eating prepared foods before shipment.