Breeding of the Raspy river stingray Potamotrygon scobina Potamotrygon scobina is one of the smaller freshwater stingrays, size ranging from 10" to 20" (25 - 50 cm) diskwidth depending on origin. The habitat of this species is from Manaus downstream in the Amazon and Pará and their tributaries. The origin of the small morph that I have breed is Rio Xingú and this variant reaches only 10" to 14" (25 - 35 cm) diskwidth (the rays from Xingu are now called orbignyi variant by scientist). These are very active rays and it is fantastic to observe them cruising through the tank. Video scobina male cruising through the tank This species prefers a water temperature in the range of 81 - 86°F (27 30°C) and is very sensitive against nitrite (NO2). If the nitrite level exceed 0.025 ppm these rays do not eat well. So a well cycled large biofilter is needed, I use Siporax as filter media. My breeding pair, (male 10.4" (26 cm) and female 12" (30 cm) diskwidth) houses in a 80" x 24" x 24" (200 x 60 x 60 cm) tank; water change is 40% per week. The tap water is treated with activated charcoal before use. My water parameters are: Temperature 81 - 86°F (27 30°C) pH 7.6 NO3 < 30 ppm hardness 180 ppm CaCO3 conductivity 460 µS/cm P. scobina has a relative small mouth, so I cut larger food items in smaller pieces. My pair feeds on bloodworms, Canadian nightcrawler, fish, mussel, shrimp and krill. I feed the adult rays once per day. First food for new imported P. scobina should be live food as nightcrawler or fresh dead fish. My P. scobina only hunt very small fishes like cardinal tetra. Sometimes it takes some weeks until they accept a new kind of food. If well fed these rays mature at an age of 18 months. For breeding attempts it is best to use a female that is larger than the male to avoid damages during the mating process. Mating and birth occurs mostly at night. Mating season starts, the male bites the female They swimm together, the male bite the female during the whole mating process They mate at the ground, male upside down. Video mating 1 Video mating 2 Young female with injuries from the male. They were together for a long time and nothing happened, then overnight this. I seperate her immediately and she recovered. Pregnant female, 5 weeks after mating the first movement of the embryo can be observed Video Movement of embryo Pregnancy last for 90120 days, litter size is 14, the diskwidth of the pups is 2.8" to 4" (710 cm). During the pregnancy the female need more food than usual, because freshwater stingrays are matrotrophic vivipar, that means they are livebearer and the female provides additional nourishment to the embryos. This happens via secretion of so called uterine milk through trophonemata (long filaments from the uterus wall which secrete a nutritive fluid). P. scobina give birth Immediately after birth the male want to mate, bottom left a newborn pup Female with pup The day after birth I separate the pups in a smaller tank. This tank is in the same circulation system as the main tank (same filtration system), so the water conditions are exactly the same as in the main tank. The pups start to feed 1-3 days after birth, I feed them blood worms 3 times per day. Most time of the day they are buried in the sand, at night they are more active. Scobina pups feed on bloodworms Video young scobinas hunt live food They grow with a rate of approximately 1 cm per month. One of my captive breed females reached sexuell maturity at a age of 18 months and a size of 10" (25 cm) diskwidth, one male matured with only 8" (20 cm) diskwidth. Bunch of pups age six months Mature captive breed scobina female two years old btw. in 2006 I sold all my scobina to start a new adventure, breeding Itaituba rays. But that will be another story.