Chilean round stingray

Where they come from

Chilean round stingrays are a temperate-water coastal species from the eastern Pacific, mostly along Chile and into Peru. Think open sandy flats, eelgrass patches, and quiet bays with cool, highly oxygenated water. They spend a lot of time half-buried in fine sand, waiting on small crustaceans and fish.

Setting up their tank

Give them footprint, not just gallons. A single adult needs something in the 8 ft by 3-4 ft range with open sand. Depth matters less than floor space. I would not house one long-term in anything under 300-400 gallons, and bigger is kinder.

Use a soft, rounded-grain aragonite sand bed, about 2-3 inches. No crushed coral, no sharp rockwork. If you want rock, build stable islands on egg crate and keep plenty of open runway. Cover every pump intake and overflow with guards so the disc cannot get sucked or scraped.

Water parameters that have worked for me: 58-66 F (14-19 C), 1.023-1.025 specific gravity, pH 8.0-8.3, undetectable ammonia and nitrite, and low nitrate (under 20 ppm, lower is better). Big skimmer, oversized biofiltration, and lots of gas exchange. Rays are oxygen-hungry, so high surface agitation helps.

Let the system mature before adding the ray. Six months of stable operation is a good target. They are sensitive to swings and to trace contaminants.

• Large footprint tank with tight-fitting lid (they can surge up walls)
• Chiller sized for your room and heat load
• 2-3 inch fine sand bed; no sharp decor
• Guards on all intakes and overflows
• Oversized skimmer and sump; high dissolved oxygen
• Reliable grounding probe and GFCI outlets (they dislike stray voltage)
• Test kits for ammonia, nitrite, nitrate, pH, salinity; keep logs

What to feed them

Start with meaty marine foods. Mine took to fresh seafood mixes quickly once it recognized the tongs. Offer small portions and watch that it actually eats and swallows instead of just mouthing and spitting. Two to four small feedings per week works for adults; juveniles need more frequent, smaller meals.

• Good staples: pieces of shrimp, squid, scallop, clam, mussel, lancefish/sand eels, marine smelt (not as the only fish item)
• Great for new arrivals: live or freshly cracked clams and mussels on the half shell, live saltwater grass shrimp, small shore crabs
• Supplements: soak foods in a quality marine vitamin (I use Selcon or similar) a few times per week

Rotate foods to avoid nutrient gaps. Rays can get finicky and some fish like smelt and krill are high in thiaminase, so mix things up and use vitamin soaks. Target-feed with long tongs or set a shallow feeding dish on the sand so you can remove leftovers easily.

How they behave and who they get along with

Most of the day they loaf under sand and make short patrols. They are calm but very aware of movement. Quick dashes can happen during maintenance or feeding.

Tankmates are tricky because of the temperature and the ray’s delicate skin. Skip nippy fish (triggers, puffers), spiny urchins, and anything that will pick at the disc or eyes. Coldwater setups do not give you a huge list anyway, so I usually run them in a species-only tank. If you try companions, look at peaceful temperate fish that ignore the ray and tolerate 58-66 F, and keep stocking light.

• Better bets: temperate gobies or sculpins that ignore the ray (research your exact species and temperature needs)
• Avoid: triggers, puffers, large wrasses, angels, aggressive damsels, sharks, urchins, crabs big enough to pinch the disc

Breeding tips

They are livebearers. Courtship can be rough, with the male biting to hold the female. I have seen successful matings only in very large, low-stress setups. Gestation runs several months, and pups are born fully formed and ready to eat small meaty foods.

• Sexing: males have claspers; females do not
• If pairing, provide a vast footprint and hiding zones so the female can get space
• Have a nursery plan: separate, sand-bottom pen with guarded intakes
• Pups take tiny strips of shrimp, squid, and chopped clam; feed small meals daily at first

Common problems to watch for

• Heat stress: rapid breathing, lethargy. Solution: reliable chiller, monitor temp daily.
• Low oxygen: surface gulping or frantic gill movement. Add aeration and surface agitation.
• Disc abrasions: from rough substrate or rock. Switch to fine sand, smooth any edges, keep water ultra-clean while healing.
• Medication sensitivity: rays are very sensitive to copper and many reef meds. Use a ray-safe plan and consult experienced keepers before dosing anything.
• Bristleworm stings: swollen patches on the disc after night feeding. Manage worms, avoid feeding on rock, consider a feeding dish.
• Internal parasites or hunger strikes: weight loss along the disc edge. Try live clams/grass shrimp, vitamin-soaked foods, and evaluate for deworming with ray-safe options.
• Water quality swings: pH drops and ammonia spikes hit them fast. Keep biofilter mature, do steady water changes, and avoid overfeeding.