Aquarium Fish-Diagnosis, Diseases and Treatments
Abnormal Behaviors Common to Sick Fish
|flaring of the operculum followed by rapid closure in an attempt to dislodge an irritant from the gills, which is suggestive of gill disease.
|rubbing against objects, which is suggestive of an ectoparasitic infestation.
|gulping air at the surface, indicating hypoxia due to oxygen-poor water, gill disease, or anemia.
|Circling (controlled) or whirling (uncontrolled)
|suggestive of blindness and neurologic disease, respectively.
|aimless, propelled motion indicative of weakness and imminent death.
|floating at the surface, which may suggest disorders such as swim bladder or neurologic disease. Or in the case of goldfish, a lack of fiber in flake food diets often results in poor intestinal motility, resulting in air accumulating in the intestines. This air causes the fish to float abnormally at the surface.
Quarantine and Initial Treatment
Common Noninfectious Disorders in Aquarium Fish
Common Infectious Disorders in Aquarium Fish
Pet fish are susceptible to bacterial, fungal, and viral infections as well as parasitic infestations. A common husbandry-related cause of infectious disease is failure to quarantine new fish before introducing them to the established system. As a result, outbreaks involving pathogenic organisms occur.
New fish should be quarantined in a separate system for four to six weeks before, their introduction into an established system with other fish. Monitor fish in quarantine for clinical signs of disease. Consider a broad-spectrum therapy, such as a prolonged immersion with a low concentration of copper (see boxed text titled “Copper treatment” on page 851) or formalin, as a prophylactic treatment.
Bacterial Infections in Aquarium Fish
Fungal Infections in Aquarium Fish
Fungal infections, another important cause of disease in fish, are usually the result of immunosuppression associated with poor water quality, stress, and other diseases. Prolonged treatment with antibiotics may also predispose fish to fungal infections. Saprolegniasis is a catch-all term for while, fuzzy mold growth on this skin of fish.
Saprdegnia is a genus of water mold that commonly infects fish and their eggs. Immunosuppression, resulting from, for example, a drop in temperature or stress from overcrowding, can predispose fish to such fungal infections. Fish with fungal infections are treated with antifungal agents given orally in food, by injections, or by the water-tome route.
Viral Infections in Aquarium Fish
Parasitic Infestations in Aquarium Fish
Treatment of Protozoa
Protozoal infestations are usually treated topically with medicated dips or baths. The distinction between a dip and a bath may vary among authors as does the preference for dosages, but in general a dip is exposure to a medicated solution for less than 15 minutes, whereas a bath is for a longer period.
Prolonged immersion treatments are those that provide a constant exposure of the medication over several days. Parasitic protozoa can be treated with formalin (0.125 to 0.250 ml 37% formaldehyde/L) as a one- to 60-minute bath; malachite green (0.1 to 0,15 mg/L) as a prolonged immersion; salt (10 to 30 g/L as a bath up to 30 min (a four- to five-minute salt solution dip for freshwater fish or freshwater dip for marine fish); or formalin (0.02 ml 37% formaldehyde/L) phis malachite green (0.1 mg/L) as a prolonged immersion.
Formalin solutions should not be used if they contain white paraformaldehyde precipitates.
Monogenean (skin or gill fluke) infestation occurs in both freshwater and marine Fish. Monogeneans are ectoparasites mat live on skin, gills, and fins. They contain a haptor (attachment organ) and have a direct life cycle. Dactylogyrus species has four points at the anterior end. an anterior sucker, four eye-spots, and a haptor with two large hooks surrounded by several small hooklets.
Gyrodactylus species has two points at the anterior end, an anterior sucker, no eyespots, and a haptor with two large hooks surrounded by several small hooklets. This monogenean is viviparous with internal embryos containing hooks. Clinical signs associated with monogenean infestation include flashing and skin disorders because of the injury to skin caused by the parasite’s attachment and feeding behavior. The hooklets on the haptor penetrate epithelial cells.
Treatment of Monogenean
Treatment of Crustacean Infestation Organophosphates
Organophosphates are the typical treatment for parasitic crustacean infestations. Dichlorvos and trichlorfon are the mast commonly used organophosphates for treating fish with parasitic crustacean, monogenean, or leech infestation. Trichlorfon (0,5 to 1 mg’L) as a prolonged immersion or dichlorvos (0.5 to 2 mg/L) as a 30- to 60-minute bath is effective.
Diflubenzuron (Dimilin–Pond Care) is a chitin synthesis inhibitor that when used at a dose of 0.01 mg/L as a prolonged immersion treatment can also rid fish of crustacean cope-pod infestation.
Copper (copper citrate or copper sulfate) is used to treat external parasites or bacterial or fungal disease. The usual therapeutic concentration is 0.15 to 0.2 ppm, except for sensitive fish. The concentration can be gradually increased (i.e. 0.01 ppm per day) to 0.2 ppm in sensitive fish. The free copper ion is the active form, whose concentration depends on the total alkalinity of the water.
A higher concentration of copper sulfate is needed to provide therapeutic concentrations of free copper ion as the alkalinity increases. Also, copper may be unstable in water with low alkalinity ( 250 nig/L). Cheated copper (e.g. copper citrate or copper EDIA) may be more stable in marine water and fresh water with high alkalinity than copper sulfate is, but its safety and efficacy are still being evaluated.