By Scott W. Michael
To ensure success in keeping a shark, it is important to start with a healthy specimen. Here are some things to look at carefully for 10 to 20 minutes in the store before bringing home a captive elasmobranch.
Eyes
A healthy shark will be alert, moving its eyes to watch things that move into its path or even a person watching through the aquarium glass. Shining a flashlight into the shark’s eye should cause the pupil to constrict, but the rate of constriction can vary from one species to another. If the pupil does not constrict or does so very slowly, it may indicate that the specimen is suffering from bacterial meningitis. In this case, do not purchase it. Also abstain from choosing any shark or ray that exhibits continually dilated pupils while the animal is in the light.
Swimming Behavior
Avoid specimens that frequently chafe against the substrate, breathe heavily, yawn frequently, swim erratically, appear disoriented or have problems maintaining their position in the tank without floating toward the surface. Species that are known to be active should spend most of their time swimming about the tank. In an inactive species, continuous swimming during the day may indicate distress. However, if food has recently been introduced, it is not unusual for a diurnally inactive species to patrol the aquarium for five to 15 minutes.
Respiration
Check the respiration rate of the animal, as indicated by the opening and closing of its gill slits. If it appears to be breathing very heavily (two to three times the “normal” respiratory rate for that species), it may be suffering from a parasitic infestation of the gills or from oxygen deprivation. If you believe that could be the problem, move on to another shark. Be aware that the respiration rate can be affected by factors unrelated to the animal’s overall health, such as water temperature, the presence of food or a threatening object (e.g., the aquarist’s hand); check and assess all of these factors before concluding that the animal is unhealthy.
Appearance
As far as physical appearance is concerned, the stomach should not be sunken, and the dorsal musculature should not be atrophied. Shrunken muscles or a hollow-looking abdomen may indicate that the animal has gone through a period of starvation or refusal to eat; these could also be symptoms of disease or parasites, from which the shark may not recover. (As a sidenote regarding rays, which are shark relatives, the pelvic bones will be very obvious in an emaciated ray, poking up against the skin near the base of the pelvic fins; this condition is a result of atrophied dorsal musculature.) Avoid specimens with patches of discoloration, excessive mucus production, blisters, open wounds or lesions, torn or frayed fins, reddish skin or curvature of the back to the left or right, or up or down.
Researching the specific shark species you want will help you to choose wisely when looking for a shark and be able to purchase a healthy specimen. Also knowing how to house and feed your new shark will help it live a long and healthy life. Take your time—and read, read, read—and try to avoid an impulse buy.
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