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Freshwater Stingrays: Points to Consider Before Your First Purchase – Part II

Hello, Frank Indiviglio here.

In Part I of this article we examined some important points concerning freshwater stingray ownership. I’ll continue here with more husbandry tips and a look at the natural history of two unique species.

Selecting an Individual: Health

Large rays may have been collected via hook, do not ship well, and usually arrive in very poor condition. Check those over 12 inches in diameter carefully. Their adjustment to captivity is much less successful than that of smaller individuals.

Do not purchase a stingray whose fins are curled upwards along their margins. For reason as yet unknown, such animals invariably expire in short order.

Identifying the Various Species

It is important that you lean to identify the commonly available species before making a purchase. Animals in the genus Dasyatis, commonly sold as “freshwater stingrays” are actually native to brackish waters (river mouths) and may fare poorly in freshwater aquariums. Others, including ceja, antenna, tiger and China rays, have unique feeding and water quality requirements, and make quite delicate captives.

The hardy, popular common or motoro ray (Potamotrygon motoro) exists in 6-8 distinct color morphs, and is difficult to identify based on appearance alone.


Freshwater stingrays have fast metabolisms and need 2-3 feedings each day; dietary variety is vital to good health.

Live blackworms, ghost shrimp, crayfish, earthworms and small fishes are necessary for newly-acquired specimens. Eventually, most can be habituated to accepting canned invertebrates and animal-based frozen foods, but live animals remain an important component of the diet.

Stingray Tankmates

While rays often get along well with each other and certain other fishes, the usually benign suckermouth catfishes (i.e. Plecostomus spp) present an unusual problem. They often latch onto stingrays’ backs, sucking at the skin and causing lesions and stress-related ailments. The reasons for this behavior have not yet been thoroughly investigated.


You would be well-advised to check the legality of stingray ownership, as 8-10 states currently prohibit the keeping of freshwater species.

A Freshwater Ray in the USA?

Most freshwater rays offered in the trade hail from South America, but others may be found in Asia, Africa and Australia.

Dasyatis sabina in FloridaInterestingly, Florida’s St. John’s River is home to a population of marine rays that have adapted to life in fresh water. The species involved, the Atlantic stingray, Dasyatis sabina (please see photo), is known to forage in river mouths, but the St. John’s River population is the only one that has become independent of the sea, even breeding in freshwater.

An Amazing Giant

Southeast Asia is home to the world’s largest freshwater stingray, Himantura chaophraya. In January of 2009 a researcher captured a massive specimen in Thailand’s Meaklong River. Spanning nearly 9 feet across and weighing an estimated 660 pounds, the giant appeared pregnant and was released unharmed.

A Hands-On Experience with Stingrays

Please be sure to visit That Fish Place/That Pet Place in Lancaster, PA (the world’s largest pet store) for a chance to hand feed our friendly marine stingrays.

I’ll cover the care of freshwater, marine and even some native stingrays in detail in future articles. Until then, please write in with your questions and comments.

Thanks, Frank Indiviglio

Further Reading

You can learn more about Southeast Asia’s spectacular giant freshwater stingray here.

Please also check out the book, Freshwater Stingrays for more on captive care.

Image referenced from Wikipedia and originally published by the user Abigor.

Dissolved Oxygen

One of the most important elements of a healthy aquarium is also one of the most overlooked. Like all animals, fish and other aquarium inhabitants require oxygen to survive. Unlike air breathing animals, fish depend on dissolved oxygen in the water to “breath”. Making sure that your aquarium has proper dissolved oxygen levels is vital to the health and survival of your fish.

Many things can affect the dissolved oxygen in your aquarium. The most important things to remember are stocking levels and cleaning. Too many fish will require more oxygen than is available in the water. Fish waste, decaying food and rotting plants are all consumed by bacteria, which also require oxygen. Regular cleaning, water changes, filter maintenance and proper feeding will ensure that the bacterial demand on dissolved oxygen is under control.

There are also many things that you can do to improve dissolved oxygen in your aquarium. Most of the dissolved oxygen in your aquarium comes from the atmosphere; this is accomplished through interaction with the water surface. Increased water surface area gives your aquarium higher potential for atmospheric interaction. Turbulence and water movement along with good aquarium design will increase your aquariums water surface area, and dissolved oxygen. Use of an air pump and air stones or a power head with a venturi aeration feature will also greatly increase your dissolved oxygen. The tiny bubbles created have huge amounts of surface area and greatly increase the potential for oxygen to dissolve into the water. Temperature also plays a significant role in dissolved oxygen levels. Concentration of dissolved gas decreases with increase in temperature, so avoiding high temperatures (above 85 Fahrenheit) in very important. Taking all these factors into account when setting up an aquarium will go a long way to ensuring your long term success.

The use of ozone, especially in saltwater aquariums, can also greatly increase dissolved oxygen. Ozone is a strong oxidizer, which when properly used, will break down organic material in the water through oxidation. This greatly reduces the biological demand for oxygen, and at the same time releasing oxygen as a byproduct of the oxidation process. Ozone use is not for the beginner level aquarist and must be used safely and properly. Use of an ORP controller is highly recommended. Ozone is typically used in conjunction with a protein skimmer, or a special reaction chamber.
Until next blog,

Species Profile: Anglerfish

One of the most interesting fish available in the aquarium hobby, is also one of the most difficult to see. Anglerfishes, also known as frogfish, are masters of disguise and camouflage, and have developed an amazing array of shapes, colors and textures to allow them to blend into their surroundings. Some look like rocks, some look like sponges, some look like algae, and some look like aliens from a distant planet.
Anglerfish get their name from the specialized dorsal spines that are found on their foreheads that resemble a fishing line and lure. They use this special appendage to lure prey towards them, then eat it whole. Anglerfish have enormous mouths for their size, and are capable of eating objects as big as they are.
Anglerfish are easily kept in aquariums, and some species do well in fairly small aquariums. Make sure that you know the adult size of the species that you are planning to keep to make sure that you are giving them enough space, Anglers can reach there adult size fairly quickly, dont be fooled by the small size that are usually found in pet stores. Some species like the Giant Anglerfish, Antennarius commerson can get up to 13″ in length. Anglers are predators, so you must be careful when choosing tankmates, if an Angler thinks it can eat something it will try. Do not keep anglers with fish of the same size or smaller, they will be eaten. Someone once described them to me as a giant mouth with a little fish attached. You should also not keep Anglers with shrimp or other small inverts that may be tasty. Other than towards prey items, Anglers are not aggressive, and make fine tank mates for larger, non aggressive species. Do not keep Anglers with aggressive species, they are easily picked upon and have little in the way of self defense.
Anglers spend most of their time sitting on the bottom, or “walking” around on their modified pectoral fins, that look more like legs in some species. You will rarely see an Angler swimming around in the open, as they are poor swimmers.
Feed Anglers a varied diet of small live foods, such as ghost shrimp or guppies. You can also train Anglers to eat fresh or frozen foods with the use of a feeding prong.
I hope that you have found this information interesting, Anglers are one of my favorite fishes, and I hope this will inspire someone to give them a try.
Until next time,