Below you will find basic information on the keeping of freshwater rays. This is a good place to start if you have not kept rays before. If you have any questions about keeping rays, feel free to email or call. I'm glad to help.
The most common tanks are rectangular and are made of glass or acrylic. Both are fine for rays. Buy the largest system you can afford. Minimum tank size will be dealt with in another section. Another option is a pond for rays. Ponds can generally be built for much less money than a large aquarium. They allow viewing of rays from the top, which some people prefer. Rubbermaid makes several different shapes and sizes of stock tanks. These are sturdy and can be a more cost effective way for keeping rays. Their 300 gallon version is a circle rougly 5 feet in diameter. There are many other companies that build similar products. Another pond option is to build a sturdy wood frame and then line it with layers of plastic sheeting. It is a good idea to use several layers to protect against possible tears (stingray stingers are sharp!). Whether you choose a tank or a pond is a matter of personal preference. Rays have bred in both types of systems and will thrive in either if properly cared for.
Tank Materials
Tanks generally come in two materials, glass or acrylic. There are benefits and drawbacks to both materials and each person much choose that which best fits their needs. Acrylic is lighter than glass and clearer. It is also stronger and easier to mold into complex shapes. Acrylic tanks are glued together with a special glue that provides for extremely strong joints that will not deteriorate like silicone used in glass tanks. Acrylic, however, is much more expensive than glass and is also softer, which means it is much easier to scratch. Acrylic tanks must be cleaned with pads and scrapers designed specifically for acrylic. Glass is much more affordable than acrylic and it is much harder to scratch. It weighs a lot more than acrylic and the joints must be sealed with silicone which generally will not last as long as the bond in acrylic seams. I've owned both types and like both. My large systems are acrylic and I prefer them that way, but for smaller tanks I prefer glass as it is much more affordable. In the end, the choice is yours. Both will be fine to house stingrays.
Tank Size
The smallest freshwater rays can still grow to a disk width of 12 inches. The largest can easily exceed 3 feet. Motoros, Leopoldi's, and Heneli's will generally stay under 24 inches, although they can reach 30". Humerosa, Hystrix, Orbignyi, and Reticulata generally max out at about 12 to 16 inches. For the smaller rays (12 inch max disk diameter) a tank with a footprint of 48 x 24 inches is the minimum size that should be used to house them. I would include no more than two of the small rays in a tank that size. As for the larger rays (24 inch max disk width) the minimum tank size for adults should have a foot print of 96 x 48 inches. Many motoros, especially males, will stay 18" or less, and can be housed in a 72 x 36 inch tank. There are rays that get larger than 24", such as Tiger rays, and they require massive systems to house adult animals. Several things must be remembered when dealing with tank sizes. First, young specimens can obviously be kept in smaller tanks when they are small. A person does not need a 96 x 48 inch tank to house one baby motoro. You must be prepared to buy a larger system for the ray as it grows, or be willing to part with the ray when it outgrows your system. Second, tank height is not nearly as important as length and width. It is much better to buy a shallower tank with a large footprint than a tall tank with a small footprint. Third, go a large as possible. Rays appreciate space to swim and will need it if they are going to thrive. It is also much easier to setup the right size system once than to keep buying and setting up progressively larger systems.
Tank Covers
Stingray tanks should be covered to prevent their "jumping" out of the system. Rays frequently swim up the sides of aquariums and can accidentally go over the edge of a glass tank that is not covered. This is much less likely with acrylic tanks that have a large lip around the top, but it is still possible for them to escape. I keep my systems covered whenever I'm not working in them.
Temperature
Stingrays can handle a fairly wide range of water temperature, anywhere from 76 to 86 degrees, with little difficulty. Generally the warmer the water, the more the rays will eat. Also, remember that warmer water provides less usable oxygen, so make sure you are cycling the water at a fast enough rate or that you add air pumps and stones to keep the oxygen levels plentiful. A good ballpark for temperature is 80 degrees. My systems run anywhere from 79 to 82 and I have heard of people having much sucess keeping rays at temps of 86 degrees. To heat your tank you will generally need a high quality heater. The problem with heaters and rays is that rays will often settle on a heater and get burned. They do not appear to sense the higher temperature. The burns can be very severe and can easily kill a ray. The best option is to keep heaters in a sump, and not in the main tank. If you are not using a sump, or for whatever reason must keep a heater in the tank with the rays, get a shielded heater that has a shroud that prevents rays from settling on the actual heater.
Water Quality
AMMONIA AND NITRITE
Ammonia and Nitrite should be kept to zero in an aquarium as both are toxic to fish and rays. Ammonia is emitted by fish and rays into the water all the time. It is also generated by decaying fish food and dead fish carcasses left in a tank. This is why you should not overfeed and also why dead fish or rays should be immediately removed from the system. Ammonia is broken down by a bacteria into nitrite, which is also toxic to fish. Nitrite is then broken down into nitrate, by a different bacteria. Nitrate is only toxic to fish and rays in high conentrations, and is generally removed by regular partial water changes. In a new aquarium, it will take several weeks for the necessary bacteria to develop to handle the breakdown of ammonia and nitrite. Rays should not be added to a system until this "cycle" has occured. If you have an ammonia or nitrite spike, one solution is to move the rays to an already established system until parameters return to normal. If you don't have access to another system, do daily 25 to 50 percent water changes until things have returned to normal. This has worked well for me in the past. If you have an ammonia or nitrite spike, you must determine the cause. It could be from overfeeding, a fish carcass that was not noticed, a clogged filter, poor water flow over bio media, an overstocked tank, or a filtration system that is too small for the system/bioload. Be sure to correct the problem.
NITRATE
Nitrate is removed by partial water changes. A weekly 25% water change is adequate for rays unless you are keeping them in a small system. If this is the case, you will have to do changes more often. Be consistant with water changes. Problems usually occur when we get lazy and put that change off for a few days. Be good to the rays, do the water change on time.
PH
Rays are usually said to prefer water of a slightly acidic level. My rays are in water with a PH of 7.2 (not acidic at all) and are fine. If your ray has acclimated to your water, is acting normal, and is eating, leave your PH alone. Trying to adjust it and keep it steady can be difficulty and the resulting roller coaster of PH levels can cause more harm than good. Only change the PH if the ray is acting stressed and PH is likely to be the cause. If this is the case, products can be purchased to alter the PH. Use it properly and keep the PH steady by frequent testing and proper use of your PH adjusting product.
TESTING
The parameters listed above are the most common tested and the most crucial to success. Test kits are available for the parameters listed above and for many other parameters. The kits for the above are generally easy to use and inexpensive. New systems should be tested daily for the first several months until parameters are at acceptable levels and have stablized. After this point, testing can occur less frequently, say every week. I would suggest resuming daily testing anytime new fish or rays are added to the system or whenever a large change is made to the system, such as adding a new filtration system. Contiue the testing until parameters are acceptable and stable again.
Food
Healthy rays will be constantly searching the tank for bits of food. They should be fed at least twice per day. There are many foods that are adequate for stingrays. I've personally fed smelt, earthworms, krill, plankton, mysis shrimp, market shrimp, and whiting filets. The favorites for my motoros are earthworms and smelt. I've found smelt to be the cheapest so far, but care should be taken not to keep rays on a mundane diet. Variety is important to avoid nutritional problems. What you feed will be largly dependent on what is available in your area. Smelt is available fresh in my area in the spring and is inexpensive. For larger rays, smelt can be fed whole with the heads/guts still intact. They will eat it all. Large canadian nightcrawlers will also be eaten whole. Fish filets should be cut into smaller pieces. For smaller rays, cut the food up so it easier for them to eat. I start my pups with live blackworms as they are small and easy for the little rays to eat. As they grow, I switch them to earthworms cut into smaller pieces. This will likely be the easiest thing to start newly purchased rays feeding. If you purchase a ray from me, I will tell you exactly what I've gotten it to eat and also what it doesnt' appear to like. One thing to avoid feeding rays is feeder goldfish. The goldfish will eventually destroy a B vitamin in rays that can eventually kill the ray. Some keepers of rays actually inject earthworms with vitamin supplements. When the ray eats the worm, it gets the vitamins too. There are several vitamin supplements designed for fish, and I think providing them to rays through their food is a good idea. If you are looking for a fast rate of growth for your rays, earthworms appear to be the best. This has been my experience and that of a few other breeders I have talked to.
Filtration Systems
There are many, many types of filtration systems available to the aquarist. Before you choose one, you should learn about the three main typs of filtration, Chemical, Biological, and Mechanical. You also need to understand how water flow rates effect your system.
WATER FLOW
You need to know how much flow is necessary in your system. The process of circulating water in the aquarium oxygenates the water. If there is not enough flow, the oxygen levels will fall and your fish will die. A flow rate of 4 times the volume of the tank, per hour, is the minimum necessary for keeping rays. Our systems turn over more than ten times the volume of the tank per hour. That is, our 480 gallon systems circulate the water at a rate of more than 4800 gallons per hour (gph). This water goes through our filter systems and keeps the water very clean. When purchasing filtration equipment, this flow rate is paramount. Be sure to buy a system that will provide enough flow for the tank size you will be using.
CHEMICAL FILTRATION
Chemical filtration uses various chemical substances to remove thing from the water. The most common is the use of activated carbon, which removes dissolved organics from the water and helps it look clear and not yellow. There are various other products that can help prevent ammonia from becoming toxic, remove nitrates, nitrites, phosphates, etc. Generally these products come in a granular form and work as the water is passed through them at the appropriate rate (see manufacturer instructions for recommended rates of flow). Here at Amazon Stingrays we use activated carbon on our systems as well as various other nitrite/ammonia/nitrate reducers when starting new systems or fixing those with problems.
BIOLOGICAL FILTRATION
Biological filtration is the break down of toxic ammonia into toxic nitrite and then into managable nitrate. All fish emit ammonia into the water. Ammonia is toxic to fish and thus must not be allowed to stay. It is broken down by bacteria into nitrite, which is also toxic to fish. This nitrite is broken down by another bacteria into nitrate, which is only toxic to fish at very high levels and is removed by regular water changes. In a new system, none of this bacteria exists yet. It will grow naturally in time, however. This is generally referred to as "cycling" a tank. It is usually done by adding a small number of inexpensive, hardy fish to the new tank and allowing the bacteria to develop naturally. This usually takes about two months or so. All that is necessary for proper biological filtration is a place for the bacteria to colonize, adequate flow of water over the bacteria, and adequate air flow to the bacteria. A system with proper biological filtration will have no detectable nitrite or ammonia.
MECHANICAL FILTRATION
Mechanical filtration is the removal of solid wastes from the aquarium. It is usually accomplished by filtering the water through a pad of some kind. The pads are changed when they become clogged.
TYPES OF FILTERS
Hang on Tank Filters-
Most small systems use filters that hang on the back of the tank. These can be very effective for small tanks, or even some of the larger ones. They generally pull water up a tube out of the tank and into the filter. The water then flows through a cartridge that has a pad (mechanical filtration) and usually some carbon (chemical filtration). There are some excellent over the tank filters out there they also incorporate a spinning wheel, like a water wheel, to the filter that provides an excellent place for bacteria to grow (biological filtration). The spinning wheel is constantly getting exposed to air and water, providing the ideal conditions for the bacteria. We use over the tank filters of this type on some of our pup grow out tanks.
Canister Filters-
Canister Filters are pressurized filters that draw water out of the tank and into a pressurized filter body that can contain filter pads, chemical media, and biological media all in one package. There are some that are quite large and capable of filtering very large systems.
Bio Media-
There are various types of bio media on the market that provide a place for benenficial bacteria to grow. Bio balls are commonly used. They are not like a regular ball that is round and smooth, but instead have grooves and protrusions that provide more surface area for the growth of bacteria. There are other types of media that resemble wads of large plastic ribbons all wadded up to provide good bacterial growth. There are many different bio media's that are all adequate for stingrays. Choice comes down to personal preference and to matching the type of filter you plan on using.
UV Sterilizers-
UV sterilizers use ultra-violet light to destroy parasites and other pests in the water. Water is pumped through a compartment that surrounds an ultra-violet light bulb. The flow rate must not be too fast, or not enough exposure to the UV light will occur. Manufacturers will tell you how much flow is required for their sterilizers. Never look directly at a UV bulb while it is on as it can damage your eyesight badly.
Filtration With a Sump-
Many large systems incorporate a sump for filtration. Water from the tank is generally gravity fed down from the main tank into another tank or tub (the sump) where filtration takes place. It is very customizable and has the advantage of adding more water volume to your system. All our large systems use a sump. In our systems, water flows out of the aquarium down PVC pipe towards the sump. It then falls through a filter pad (mechanical filtration). Water is pumped out of the sump to a bio-reactor and also to a UV Sterilizer.
