Stingrays need clean water with 0 ammonia, 0 nitrite and preferably 0 nitrate.
If there is a water quality problem, they will suffer well before normal fish do. If you monitor the underside of the stingray, they normally have a white/ cream belly. When the water quality isn't good, their belly goes pink or red, depending on how bad the conditions are (pink is minor, red is bad). If they have a pink or red belly, you need to do a huge (70-90%) water change, gravel clean the substrate, and clean the filter straight away. Make sure any new water is free of chlorine/ chloramine before it's added to the tank.
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MEDICATIONS
Stingrays are sensitive to most fish medications, and clean water and salt is the best remedy for most issues. Freshwater stingrays tolerate salt quite well because they originate from marine ancestors. For the freshwater species, you don't have salt in the tank all the time, but you can sue salt to treat them if they get minor injuries. For brackish species, they need salt all the time.
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FOOD
Stingrays will eat most food that sinks to the bottom but have a preference for prawn/ shrimp, fish and various marine based meats (squid, octopus, mussel, etc). The smaller ones (juveniles and babies) will also eat insect larvae, brineshrimp, etc.
Most stingrays tame down really well in aquariums and will take food from your hand after a week or two. This helps you check their health. You offer food near the surface and they swim up and press their belly against the glass. You can then check it for colouration.
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TANK MATES
As a general rule you don't keep rays with other fishes because the fish might bite the rays or the rays might eat the fish. Also having other fish in the tank means the water quality will go off quicker and you will need to do more water changes. If you want fish in the tank with them, get something peaceful that lives near the surface.
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PLANTS & ORNAMENTS
Having lots of plants in the tank can help keep the water cleaner. However, the rays might knock some plants about, especially new plants that haven't developed a decent root system. Amazon sword plants have a good root system and usually hold up well unless the rays dig under them. You can grow plants in plastic pots and this will allow you to have plants and the rays won't knock them about. Floating plants are also good to have.
Have sand or smooth fine gravel, preferably sand so the rays can bury themselves.
Don't have any sharp objects in the tank. Have minimal rocks and driftwood because the rays need open space to swim and move around.
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TAIL SPINES
All stingrays have at least one spine on their tail and many have 2 or 3 spines. Some are poisonous and others are not. However, most have mucous and bacteria on the spines and if you get hit by the tail and the spine scratches or penetrates the skin, it can easily become infected. If you do get a stingray spine in you, go to a doctor and have them remove the spine and clean the wound. Then monitor it for infection.
Stingrays do not normally whip people with their tails and it is only used for self defense. The most common spine injuries occur to people's legs and feet when they step on a ray. The ray instinctively reacts by whipping its tail up and stabbing whatever is on its back. I have never heard of anyone being hit by a ray's spine when the ray was kept in an aquarium, and the ray wasn't being tormented.
