The Stingray Guide
The goal for many a fish keeper (including myself) is to get a large tank, and keep the fish they've read all about, and admired for months, if not years. For me, there is no better fish in aquaria than the stingray. But, they must be cared for correctly, and this guide to freshwater stingrays will hopefully be a good starting place to look.
Firstly, there's one thing that needs to be taken into account when keeping a big fish (or any animal for that matter) and that is the size of the environment you can provide for them. In the case of rays, they need very large tanks. Even the smallest species, Potamotrygon scobina will need a minimum tank size of 48lx30wx20h for a trio (two females, and one male). The larger species, like Potamotrygon motoro will need tanks with much larger volumes, and widths of 32" or more. And remember, these tanks weight hundreds of kilos, and may require structural re-enforcement, and in most cases wont be able to go upstairs.
Another thing which must be considered when buying a stingray, is the filteration and powerheads that will be required. Rays will need their tank to be filtered vigorously, with 5x the tanks volume going through the filter/s, so if your ray tank was 250 US gallons, then 1250 would be the bare minimum water volume that would need to go through the filter, and if there are other tankmates on top of the rays then they would need to be accounted for also. The best type of filteration for the tank would be a larger wet/dry trickle tower sump but one or two external (canister) filters which are appropriately sized, like one from the eheim external range would be sufficient, and then an internal filter, which will act as a powerhead as well. Rays love well oxygenated, fast flowing water, so a powerhead should be added to each end of the tank. On a 250 US gallon tank, two 800-1000lph powerheads placed at each end would be sufficient, as well as any movement from the external filters.
Internal heaters can cause severe burns to a stingrays disc, and so the heater must be covered appropriately, using a heater guard. A good idea is to have two heaters in your tank instead of one, this way, if one of them fails, then at least there is a back up plan in place. Larger tanks may require several. They are best placed near a filter outlet so that the heat is distributed around the tank more efficiently.
For a ray tank, lighting is fairly unimportant, because rays are usually kept in fairly deep tanks, so not as much light will penetrate to the bottom on the tank anyway, and plants often wont be kept in a ray tank, as the rays would simply eat them. However, a nicely lit tank will show off the rays colours and makes the tank more of a centre-piece.
There are conflicting views on whether or not a substrate is required in a stingray tank, with more and more ray keepers using very fine gravel to sand. Sand is annoying, because it sticks to rays, but they can bury in it. It looks better than a bare bottom, but is harder to clean, and waste and uneaten food can accumulate. Having a bare bottom may look unattractive (to some) but it is much easier to clean, and the rays can locate their food easier. Very fine gravel is in between, because rays don't really bury in it, and its still hard to clean like sand, but it doesn't stick to the rays like sand does. So the debate will continue, substrate or no substrate.
Rays come from the soft, acidic waters of the Amazon, and surrounding tributes and rivers. They do however adapt very well to typical water used in our homes, with a couple of members from this forum keeping them in the hard water of London. Temperatures should be about 81 to 83 degrees Fahrenheit, but some species may require a higher temperature. They are quite adaptable, but they will not take kindly to any slacking from their owners. Water quality is vital, and water changes must be kept on top of. Two 20% water changes are undertaken each week by the general ray owner, which is a lot of water on a 250 US gallon tank.Would you have the time?
Being large animals, with long tails, rays need as much room to manoeuvre as possible (hence the extra wide tanks). Because of this, decoration must be kept to an absolute minimum, and most ray keepers don't bother with any decoration, not only because of space, but also because of the possible dangers with sharp edges which can cause injury, and also decoration takes some of the focus off the tanks inhabitants.
Rays are dangerous animals, with the general public being alerted of their danger with the death of Steve Irwin, and even though he was particularly unlucky by being struck in the heart by the tail, the danger is still there in the confines of an aquarium. They only use their sting for self defence. At the end of their long tails is a venomous stinger, which are shed every 3 to 6 months. This should be removed using suitable gloves (brand new or used specifically for the rays). Care must also be taken when handling rays, or when doing any tank maintenance. If you do get stung, get medical attention as soon as possible.
Newly imported stingrays are most vulnerable in the first few weeks after arriving to either the fish shop, or your home, especially when they are young. There are a number of ways that you can tell if a stingray is healthy. The first is that stingrays are always hungry, ask the person who you are buying it off to feed it, and if you are unsure, don't buy it. On older rays, fat tails (near to the body, not at the end) are a good sign of health, as it means that their food supplies/reserves are up, as they store it there when adult. You shouldn't be able to see any bones sticking out. For young rays, good ways of fattening them up is to use earthworms, which you can get from a fishing bait shop, or online. One very bad sign of health is if the ray is in what known as a death curl, which is where the edges of the rays disc are upturned. Death often occurs when rays are in this position, hence the name. The disc is upturned because of an irritating fungal or bacterial infection on the underside of the disc. Another thing which can be sometimes found on newly imported rays are parasites. They aren't very nice, but can be removed with ease (as long as the ray isn't stressed) by using tweezers (apparently¦.)
Rays are big animals, and will require copious amounts of food. For young, newly imported rays, one of the best ways to get them fattened up is to use earthworms (available for mail-order online, or in most fish bait shops). If they are too big, they can be chopped up. Bloodworms are also a relished food for young rays, both live and frozen, but are generally too small to be substantial for adults. Live rivershrimp (caught in the Themes estuary) are great food for young rays and adults alike, and it provides the rays with some exercise and they have loads of nutritional value. Other foods include muscles, which are a staple diet along with cockles and shrimp. To prepare these foods when frozen, simply thaw them out (the fleshy insides of the cockles and muscles), cut them up (if required) and drop into the tank. Another food which is easy to use is lance fish, which can be prepared by cutting off filets, or feeding whole (thawed, in both cases).
Sexing stingrays is fairly easy, especially on adult rays where the differences can be seen from above, but younger males may need to be seen from below to be sure. Males have what are known as claspers, which are located on the underside of the ray, below the tail. There are two of them, and they are the males genitals. Seeing a picture is the easiest way, and you will be able to see the "add-on" which the male possesses, but the female doesn't.
Stingrays breed in a very aggressive manner, where the male will get under the female, and hold her in a tight grip with his jaws, by biting her disc edge. For the best results, the male should be smaller than the female, so that he does not overpower the female, which can lead to terrible injuries to the female. Another thing which can help is to have more than one female in the tank with the male, with a ratio of two females to every male often working best, so that the female wont be bothered constantly by the male (his attention may wander to the other female). Rays are livebearers, and will give birth to live young after a pregnancy which can last 130 days or more (not much is know about the length of pregnancy's, as not very many people have bred them in captivity). Between 1 and 4 pups are born at a time (need a bit of backup on that one).
Rays don;t come in many shapes, only "flat" and circular, but they do come in many sizes. The smaller species can stay at a mere 12", whereas giants like Potamotrygon menchacai get to sizes of 40". I will give a brief description of each of the more commonly traded species giving details on sizes etc.
This stingray is considered the smallest of the freshwater stingrays, attaining a size of 12" aquaria. They usually have a light background colour, with even lighter spots. A beautiful species, which stays small.
These rays stay small, reaching 14", with 16" being a large specimen. They don't have strict patterns, and have more swirls of colour than spots. They are the second most available ray in fish shops, and are reasonably cheap. They are quite easy to keep, hence their popularity, and so price.
This species is not commonly traded, but is a nice, and reasonably a small (as far as rays are concerned) species, staying at around 16", so a 60x32x24" tank would suit a pair for life, along with a few other tankmates, but be careful, make sure the tankmates don't need hides, because you want as little decoration as possible.
This is a very hardy stingray, perfect for beginners. It gets to 16" and comes in a variety of patterns. Quite a slow/peaceful feeder.
This ray will stay at 16", will require a 32" wide tank, and 5 feet long, at least. A very nice looking ray with patches of darker colours, on top of a lighter background (usually).
This is some peoples favourite ray, because of its small, white dots on a solid black background. Its appealing in other ways too, staying at a small 16", it's a superb addition to the smaller ray tank (even though it would need to be 60x32x24h" min). These rays do however have their drawbacks. They aren't cheap. They are the second most expensive rays you can buy. They are often called P14's, which is their number in the system, like with L number plecs.
This ray is very uncommon, hardly ever seen in shops, not on the high street or online. They are however, a beautiful species, with a back that consists of hundreds of dark yellow spots, on a greyish green background.
This is the top ray to own, due to its beautiful markings and how rare they are, which makes them the most expensive freshwater stingray. I'm slightly unsure of their scientific name and overall size, but something around the 24 to 28" mark is likely. They come with many different markings, which can increase their value remarkably, depending on the colours and patterns.
This is another ray which has beautiful markings, with a huge contrast between its background colours, and those on top. They have long tails, and with a disc size of 30", but the tails can be another 15" long, sometimes moreâ€¦.They will, therefore need a giant tank, and most aquarists will not be able to accommodate them. They are very peaceful, and will become stressed if kept with more aggressive rays like motoros. They are most commonly called Tiger Rays. T1KARMANN says that they can get to 30" disc size or more....
Another large species, these rays will get to 22", and are only kept in huge tanks, holding often thousands of gallons. They are peaceful feeders, like Tiger Rays, and make perfect tankmates for them, in the right size tank. Their common name is the Flower Ray, because of their beautiful flower like pattern.
This ray is the most common of the freshwater rays that can be found in your local fish shop. They have a simple spot pattern, often in orange, with a dark ring around it. Other variations are available, like "marbled" motoros which have more spots than the normal motoro, and "blue" motoros. They get big, unfortunately, with females reaching 24" .They have been bred numerously in captivity, and are a hardy species.
This species looks, at first like a bigger version of the Potamotrygon itaituba, but they have larger spots, which are often longer, rather than a perfect circle. Variations exist, including ones with smaller spots around the main white spots, or in between them. These rays get to about 22".
These rays get very large, and have marking similar to that of the itaituba and leopoldi rays, but their spots are round, like those on the itaituba's, but they are bigger. These rays get to a 22" disc size.
I hope that this guide covers some of the basics of keeping freshwater stingrays, and that you can appreciate their beauty, but having said that, there is a big responsibility involved, such as food, dechlor, medication and electricity bills. If money is an issue, please do not skimp, make sure they are being well looked after, and even when they grow, and are much larger, that you can still provide for their needs, and before buying ANY animal, please do your own research, through books and other peoples expericanes.
The Aqualog Special Freshwater Stingrays of South America is a great book for further reading.
If anyone has any additional information they wish to add please do so, or any errors, corrections or anything you disagree with then please say, I would like to make this as helpful as possible. I have added some species size information, gathered from T1KARRMANN, so thanks alot.
Thanks for reading, Mike