Housing Freshwater Stingrays
Freshwater stingrays are inherently messy fish, so the bigger the aquarium is, the better. These fish require good water quality, and a larger tank means less drastic fluctuations in water chemistry and/or temperature over any given time. It will also cut you some slack in terms of how often you need to perform routine water changes. Many keepers of rays recommend tanks at least in the 90-180 gallon range. However, the most important consideration in selecting your aquarium is horizontal surface area, as rays spend most of their time on the bottom actively searching for food. Housing possibilities are not limited to glass tanks; one gentleman in my area who currently owns 32 stingrays houses them in a series of 1500-gallon swimming pools in his basement, so there are other options out there.
Keep it minimal. Live plants are not really an option unless, by some miracle of aquatic engineering, they can be kept out of your ray's way, because they will be dug up. Plastic plants are fine, as long as you're prepared to re-bury them on a regular basis. Do not use decorations with sharp edges-- you don't want your ray's disc to get cut or scraped. The more unobstructed swimming room is provided, the better.
A word of advice on heaters: keep them covered over and out of the ray's way to prevent your pet from being burned. There are plastic heater covers available in most major pet supply outlets, so do your ray a favor and purchase one as soon as possible. Tronic manufactures guards for most sizes of heaters, but you can make your own relatively inexpensively if you have the time and the patience.
A heater guard, made by Tronic.
As far as substrate goes, rays seem to enjoy a thick layer of rounded, minimally abrasive sand or gravel in which they can bury themselves if they feel threatened. They also love to dig and blow in the substrate in their constant search for food.
If you decide to go with sand, make sure it is free of silica and is suitable for freshwater aquariums (i.e. - no crushed coral sand or other marine substrates). Estes sand or CaribSea's "Torpedo Beach" and "Peace River" will work quite well.
Many aquarists keep their rays in bare-bottomed tanks without any major problems. Tanks without substrate can be easier to vacuum, and rays can locate their food more easily, but they don't get much traction when they try to scoot around on the bottom, and they just seem uncomfortable being unable to cover themselves or exercise their natural instinct to dig. Tanks with a more natural atmosphere are also more aesthetically pleasing, at least in my opinion. For these reasons, I recommend going with the substrate over the minimalist look. However, I would like to emphasize that there are advantages and disadvantages to either way of doing things.
Maintaining good water quality and frequent water changes are the keys to successfully keeping freshwater stingrays.
Using a good quality water conditioner during water changes is also extremely important. Most city tap water is treated with chloramines in order to kill any parasites that may be lurking within the water supply. However, chlorine and ammonia are also toxic to fish, rays being particularly susceptible. Water conditioners are designed to render these chemicals harmless to aquarium fishes and invertebrates. I've had good luck with both Amquel Plus by Kordon or Stress Coat by Aquarium Pharmaceuticals.
Some regularly aquarists add uniodized salt to their tanks to keep pathogens at bay. This is a good idea if your ray is healing from an injury or fungal infection, but it should not be administered otherwise. As long as you follow proper quarantine procedures and keep the water quality high to begin with, you should not end up with any sick rays on your hands.
Since rays are Amazonian fishes, they do best at a slightly lower pH. If you live in an area with extremely hard water, such as the southwestern United States, you will probably need to use reverse osmosis or some other system that reduces the carbonate hardness. You can also try adding some driftwood or a CO2 system to reduce a slightly higher pH naturally.
Here are some general guidelines for stingray-friendly water chemistry. They are generally tolerant of some deviation as far as pH and nitrite are concerned, but keeping the ammonia levels extremely low to non-existent is required. I have heard of some ray owners who accidentally allowed the water temperature to drop as low as 65º F without any long-term effects, so you have some leeway there. However, rays really do not do well at temperatures higher than around 83º F.
Stingrays are extremely active animals with huge appetites, and consequently, they generate a great deal of poop. Healthy ray poop is medium to dark brown in color, with some variation depending on what was eaten, and it generally comes out in long spiral ribbons. It is very soft and will easily break apart if disturbed, which fouls up the water. It is for this reason that frequent water changes and effective filtration are so important.
Water Changes - how much, how often?
There are many different theories out there regarding how much water should be changed at once and how frequently it should be done. It is difficult to give a specific recommendation because it really depends upon how large your aquarium is and the number and type of fish you're keeping. When I had my two rays in a smaller tank, I was doing 20-25% water changes almost every day, but since upgrading to the 180 gallon, I can get away with changing about 15-20% once or twice a week. Try to siphon the poop and other debris off the bottom whenever you get a chance. So I guess my final answer is that it depends, and you will have to try to guage this yourself based on your water chemistry measurements and how quickly the tank seems to get dirty.
You will definitely need a good filtration system, something that can cycle the entire volume of the tank 3-4 times per hour. I have two types of filtration in my 180 gallon: a biological filter attached to a spillover kit, and two Whisper 60's to filter out any of the larger debris floating around in the lower levels of the tank.
© 2007 K. Birkett.