Freshwater Stingray (Motoro) Breeding Guide

How advanced keepers breed the motoro stingray (Potamotrygon motoro): sexing by claspers, matrotrophic livebearing, 9-12 week gestation and raising newborn pups.

Overview

Potamotrygon motoro is a livebearing freshwater ray that has been bred regularly in captivity in recent years, but only by advanced keepers. It reproduces by matrotrophic viviparity, in which specialised villi in the female's uterus secrete histotrophe that nourishes the developing pups after their yolk sacs are depleted.

Sexing

Males carry a pair of sexual appendages called claspers, one on each pelvic fin, extending backward from the inner fin surface. These are used during mating and are visible even in juveniles, though smaller. Females lack claspers.

Conditioning

Maintain prospective breeders on a high-quality diet and pristine water. Recommended parameters are about 24 to 27 degrees Celsius, pH 6.0 to 7.5 and hardness of 1 to 12 degrees. Reaching maturity can take several years, so patience is required when raising juveniles toward breeding.

Spawning Behavior & Trigger

Courtship can be violent: males chase females relentlessly and bite during positioning, and males of this species are among the most aggressive at this time, so close monitoring is needed. The pair must align belly to belly for successful mating, which lasts only seconds.

Egg & Fry Care

Gestation in captive specimens typically lasts between 9 and 12 weeks, shorter than in the wild, with litters of one to eight pups. Newborns have a small yolk sac that sustains them for up to a week; after it is absorbed they require high-quality live and frozen foods offered several times daily. With good water changes and feeding, growth is rapid.

Common Challenges

The space and water-quality demands, the venomous barb, violent courtship and long time to maturity make this a project only for experienced keepers. Aggression during mating must be managed to avoid injury to the female.