Fish lice
Stingrays in captivity are usually not susceptible to the common diseases of other tropical fishes. Occasionally, newly imported specimens may carry fish lice (Argulus spp.). These ectoparasites appear as small brown circular spots, about 2-3 mm in diameter, and are more readily seen on light-color stingrays. Fish lice are usually only observed in small numbers (i.e., 2-3) and if gently touched the parasite will skitter across the skin of the stingray. When on the dorsal surface, fish lice can be removed readily with forceps. When on the ventral surface, removal is more difficult as it is difficult to invert stingrays. In these circumstances, it is easier to pinch the parasite through a net, from underneath, in order to remove it. Sudden heavy outbreaks of fish lice may occur within an exhibit, without the addition of new stingray specimens. These outbreaks are probably caused by a few unobserved parasites successfully reproducing. Dimilin or diflubenzuron (e.g., Anchors Away®, Jungle Laboratories Corp., USA), a chitin inhibitor non-toxic to fishes, is effective at treating fish lice outbreaks at a dosage 2,650 mg l-1. This treatment should be repeated once after a two week period.
Fungus
Fungal infection is the commonest disease of freshwater stingrays. The first obvious sign of an underlying health abnormality is often a fungal infection of the skin. Fungal infections appear to occur secondarily to external injuries, bacterial infections, or chronic stress. Fungal infections caused by the freshwater cotton wool fungus (Saprolegnia spp.) are often seen on the tail, especially where a piece of air tubing has been placed over the spine, or at the tip of the tail where minor injuries may have occurred during handling. These infections appear as small cotton-like tufts and generally are not difficult to cure. Treatment with antibiotics appears to be an effective means of eliminating fungal infections. Fungi are generally not susceptible to antibiotics, it is likely that the successful treatment of fungal infections is a secondary effect of treating an underlying bacterial infection.
Antibiotics
Furanace (e.g., Nitrofurazone, Novalek Inc., USA) may be added directly to aquarium water to treat minor infections; however, injectable antibiotics are generally more effective and preferable. Enrofloxacin (Baytril®, Bayer Corp., USA) at 0.25 mg kg-1 (daily or every other day), or ceftazadime pentahydrate (Fortaz®, GlaxoSmithKline Inc., USA) at 10.0 mg kg-1 (every other day), administered intramuscularly for 7-10 days, may be used to treat bacterial infections secondary to external injury. Rays requiring injection should be netted and held just below the surface of the water, to prevent excessive struggling. The process is facilitated if the spiracles remain submerged. If two people are available, the body of the stingray can be supported from below with one hand, while the injection is being given with the other hand. The second person can hold the net. Injections should be given intramuscularly. The preferred injection site is slightly to the right or left of the spine, about halfway between the line of the eye and the base of the tail. The needle should be inserted to a depth of ~5.0 mm, at a low angle, rather than perpendicular to the body. Care should be taken to avoid being within range of the spine when giving injections. Before handling or administering any form of medication it is advisable to seek veterinary advice.
Stingrays in captivity are usually not susceptible to the common diseases of other tropical fishes. Occasionally, newly imported specimens may carry fish lice (Argulus spp.). These ectoparasites appear as small brown circular spots, about 2-3 mm in diameter, and are more readily seen on light-color stingrays. Fish lice are usually only observed in small numbers (i.e., 2-3) and if gently touched the parasite will skitter across the skin of the stingray. When on the dorsal surface, fish lice can be removed readily with forceps. When on the ventral surface, removal is more difficult as it is difficult to invert stingrays. In these circumstances, it is easier to pinch the parasite through a net, from underneath, in order to remove it. Sudden heavy outbreaks of fish lice may occur within an exhibit, without the addition of new stingray specimens. These outbreaks are probably caused by a few unobserved parasites successfully reproducing. Dimilin or diflubenzuron (e.g., Anchors Away®, Jungle Laboratories Corp., USA), a chitin inhibitor non-toxic to fishes, is effective at treating fish lice outbreaks at a dosage 2,650 mg l-1. This treatment should be repeated once after a two week period.
Fungus
Fungal infection is the commonest disease of freshwater stingrays. The first obvious sign of an underlying health abnormality is often a fungal infection of the skin. Fungal infections appear to occur secondarily to external injuries, bacterial infections, or chronic stress. Fungal infections caused by the freshwater cotton wool fungus (Saprolegnia spp.) are often seen on the tail, especially where a piece of air tubing has been placed over the spine, or at the tip of the tail where minor injuries may have occurred during handling. These infections appear as small cotton-like tufts and generally are not difficult to cure. Treatment with antibiotics appears to be an effective means of eliminating fungal infections. Fungi are generally not susceptible to antibiotics, it is likely that the successful treatment of fungal infections is a secondary effect of treating an underlying bacterial infection.
Antibiotics
Furanace (e.g., Nitrofurazone, Novalek Inc., USA) may be added directly to aquarium water to treat minor infections; however, injectable antibiotics are generally more effective and preferable. Enrofloxacin (Baytril®, Bayer Corp., USA) at 0.25 mg kg-1 (daily or every other day), or ceftazadime pentahydrate (Fortaz®, GlaxoSmithKline Inc., USA) at 10.0 mg kg-1 (every other day), administered intramuscularly for 7-10 days, may be used to treat bacterial infections secondary to external injury. Rays requiring injection should be netted and held just below the surface of the water, to prevent excessive struggling. The process is facilitated if the spiracles remain submerged. If two people are available, the body of the stingray can be supported from below with one hand, while the injection is being given with the other hand. The second person can hold the net. Injections should be given intramuscularly. The preferred injection site is slightly to the right or left of the spine, about halfway between the line of the eye and the base of the tail. The needle should be inserted to a depth of ~5.0 mm, at a low angle, rather than perpendicular to the body. Care should be taken to avoid being within range of the spine when giving injections. Before handling or administering any form of medication it is advisable to seek veterinary advice.
