Goldfish & Koi Swim Bladder Inflammation & Dropsy

Common Indicators: Abnormal swimming & resting positions, sluggishness, abdominal swelling, darkening, loss of appetite, mucus

The term ‘dropsy’ when referring to issues with goldfish and koi (salmonid fish — of which carp related fish are a part) can be frustrating. This is because ‘dropsy’ is a clinical-sign rather than a disease caused by a single agent or organism. Dropsy generally refers to any infection of the swim bladder or internal swelling resulting in loss of proper buoyancy and swim control in these fish. Causes for this can range from tumors, intestinal blockage or bacterial infection, and more.

Due to any of these causes, aquarists can potentially observe the fish either remaining on the bottom, or consistently floating to the top, possibly combined with odd swimming positions such as tilting to the side, becoming inverted. Even when not caused by bacteria, secondary infections such as Aeromonas can occur in these circumstances — as well as signs of related problems like bulging eyes or scales becoming protruded from the body (lending this disorder ‘pinecone disease’). However, even in the case of bulging eyes and ‘pinecone’ scales, this could be a sign that a female fish contains eggs. Thus, diagnosis becomes difficult.

Because of the variety of causes manifesting in similar clinical-signs, there is no single, consistently reliable treatment that can be claimed to treat these visible signs.

It is generally understood based on scientific literature on the subject, however, that bacterial infection is among the more common causes of this disorder. The disease ‘Spring Viremia of Carp (SVC) caused by the virus Rhabdovirus carpio has been identified by Edward J. Noga as displaying the clinical signs associated with dropsy and as being a potential cause of swim bladder infection. While it is possible for antibiotics to be used for secondary infections often accompanying viral causes, because it is a virus disinfection and quarantine to prevent spread is advised, but not a cure if this is the underlying cause.


Bibliography & Further Reading:

Noga, Edward J. “Fish Disease Diagnosis and Treatment.” 2nd Ed. John Wiley & Sons; 2010

Stoskopf, Michael K. “Fish Medicine.” W.B. Saunders; 1993

Dixon, P. (SVC contributor), OIE Aquatic Animal Commission, Ed. “Manual of Diagnostic Tests for Aquatic Animals.” World Organisation for Animal Health; 2009


Meyer, Stephen M. “Dreaded Dropsy: Dropsy is an external sign of an internal problem” (Aquarium USA Magazine);

Way, K. “Rapid detection of SVC virus antigen in infected cell cultures and clinically diseased carp by the enzyme-linked immunosorbent assay (ELISA).” Applied Ichthyology; 1997

Advisory: The information contained in this article entry is for informational purposes only, and is not a substitute for consultation with a veterinary professional nor treatment under the supervision of a veterinary professional. New Life International does not guarantee the accuracy or completeness of the information nor of the sources cited as reference. This articles is not a diagnostic tool or reference, nor should be considered treatment advice by New Life International.

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