Motoro Stingray

fish description – Motoro Stingray Care Guide ($Potamotrygon\ motoro$)

Category	Detail
Scientific Name	Potamotrygon\ motoro
Common Name	Motoro Stingray, Ocellate River Stingray, Peacock-Eye Stingray
Origin	Amazon, Orinoco, and Paraguay River Basins (South America)
Adult Size	18–20 inches (45–50 cm) disc width (larger in the wild)
Temperament	Peaceful toward large fish, bottom-dwelling carnivore
Lifespan	10–20+ years
Care Level	Advanced (due to size, sensitivity, and venomous spine)

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Appearance and Sexual Differences

 

• Short Description: This fish is easily recognized by its flat, nearly circular disc shape, long whip-like tail, and venomous spine.⁹ Its dorsal surface is dark brown/black with conspicuous pale spots or rings (ocelli), which give it the peacock-eye name.

   

• Coloration: Dark base color with vivid yellow, orange, or cream-colored spots.¹⁰ Males develop a sharp, recurved spine on the inner edge of their pectoral fins (clasper) during breeding. Females are generally larger and fuller-bodied than males.¹¹

   

• Fins: Broad, flat pectoral fins form the main disc.¹² The tail contains one or more venomous barbs used for defense.¹³

   

• Behavior: Primarily nocturnal and solitary, spending most of its time resting or partially buried in the substrate (sand is essential).¹⁴ They possess electroreceptors (Ampullae of Lorenzini) to locate prey buried in the sand.¹⁵ They are highly sensitive to stress and poor water quality.¹⁶

   

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Tank Requirements and Water Parameters

 

• Minimum Tank Size: 300 gallons (1135 liters) is the absolute minimum for a single adult.¹⁷ The tank must have a large horizontal footprint (e.g., 8 feet long x 3 feet wide) to allow for swimming and turning.¹⁸

   

• Schooling: Generally peaceful and can be kept singly or in groups (5+) in exceptionally large tanks.¹⁹ Keep only one male with multiple females to reduce aggression.²⁰

   

• Temperature: Tropical range: ²¹$75^\circ$–²²$82^\circ\text{F}\ (24^\circ$–²³$28^\circ\mathrm{C})$.²⁴

   

• pH Level: Soft, neutral to slightly acidic water: 6.0 to 7.5.²⁵ They are extremely sensitive to nitrates, ammonia, and nitrites.²⁶ Massive filtration (sump/canister) and large weekly water changes (30–50%) are mandatory.²⁷

   

• Aquascape: Requires a deep bed of fine, soft sand substrate (essential for burrowing and protecting their underside/barbels).²⁸ Decorate with smooth driftwood and rocks; avoid all sharp objects.²⁹ The tank top must be securely locked to prevent jumping. Heaters should be guarded or placed in a sump.³⁰

   

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Diet and Feeding

 

The Motoro Stingray is a carnivore that forages for benthic invertebrates.³¹

 

• Staple Diet: Should consist of high-quality meaty, sinking foods.³² Examples include earthworms, shrimp (prawns), mussels, squid, and fish fillets.

   

• Supplementation: Offer a varied diet of live or frozen foods (bloodworms, krill) at least twice daily.³³

   

• Schedule: Feed 1–2 times daily. Avoid feeding mammalian meats (beef heart, chicken) as the fat is indigestible and harmful to their liver.³⁴ Train them to eat non-live food to prevent disease introduction.

   

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Compatibility

 

• Caution: Venomous spine requires extreme caution during maintenance.³⁵ Will eat any small fish that can be caught or swallowed. Highly sensitive to chemicals and copper-based treatments.

   

• Good Tank Mates: Peaceful, large, robust fish that occupy the mid-to-upper water columns, such as large Arowanas, Bichirs, Large Catfish (e.g., Hoplo or Raphael), and large Cichlids (e.g., Severums, Jaguars). Avoid fin-nippers and overly aggressive fish.