Stingrays will eat a wide variety of foods. Maintaining a varied diet is extremely important in captive animals, as monocultural diets incur a risk of nutritional deficiencies. Stingrays are very active, and should be fed at least once a day, preferably twice or even three times daily. The daily diet can be varied in order to create some environmental enrichment as well as balanced nutrition for rays.
First foods for newly acquired rays should be blackworms or tubifex worms. These foods seem to be most readily accepted, and are small enough to be inadvertently ingested either by mouth or through spiracle, thereby giving ray an opportunity to taste these possibly unfamiliar foods by chance. Foods that have been used for very small specimens, such as teacup rays, are small insect larvae such as mosquito larvae, small shrimp known as ghost shrimp or glass shrimp, live adult brine shrimp, and blackworms. Chitinous foods such as shrimp provide less nutritional value than do soft-bodied foods, and so should not be used as sole food items.
The best way to be certain that your new stingray is feeding is to watch spiracles as ray passes over food on bottom of tank. If it is eating, you will see spiracles opening and closing rapidly, or fluttering, as food is ingested and water is passed from mouth and out spiracles. Once you observe a newly acquired ray readily feeding on black-worms or redworms introduce finely chopped night crawlers in small quantities. Once stingrays recognize these as food, most will readily eat them. Later, experiment with other types of food.
Types of Food
Feed live foods, including blackworms or tubifex worms, in quantities adequate to allow a small amount to be left in tank so rays can browse later. However, when cleaning substrate, note whether a significant amount of living worms is present; blackworms and tubifex worms will colonize substrate if not eaten and add to nitrogenous waste production in aquarium.
Nonlive, Nonaquatic Foods
Chopped earthworms, redworms, or night crawlers and any nonlive, nonaquatic foods should be fed in smaller quantities to prevent any overlooked food from decomposing in tank. Keep in mind that stingrays have relatively small mouths-a 10-inch (25-cm) ray may have a mouth that is 1/2 to 3/4 inch (13 to 19 mm) wide, so chopped food items must be small enough to be eaten easily. If a ray ingests a piece of food and repeatedly spits it out and ingests it again, this usually indicates that particle is too large. Some ray species, such as antenna rays, have extremely small mouths relative to their size.
Once acclimated, rays often develop techniques for eating larger pieces of food; for example, newly imported rays may have difficulty consuming even small chopped pieces of night crawlers. Eventually, however, they learn to eat an entire worm by sucking it into their oral cavity without chewing. Newly acquired rays also often ignore feeder goldfish but they quickly learn to chase down and consume feeders, even learning where they hide in tank.
Commercially Prepared Foods
Stingrays may learn to eat other unfamiliar foods such as brine shrimp, pellet foods, or other commercially prepared foods. While there is probably no harm in offering these foods to rays, it is best to use fresh, live, or frozen foods as dietary staple. Although stingrays often do not initially accept frozen or other nonliving foods, they may soon learn to eat these foods after they have been acclimated. A benefit of frozen foods is that they are less likely than live foods to introduce diseases or parasites.