Abstract

Reports of urolithiasis in teleost fish do exist, but are likely underreported in the literature. While the etiology of various types of stones is well elucidated in many terrestrial species, their close interface with the aqueous environment and varying physiologic mechanisms for regulating mineral and ion uptake and excretion make prevention and treatment a particular challenge in teleost species.^1,2,3,4,5 Over a two year period at the Florida Aquarium, two separate events occurred in which groups of fish appeared to be uniformly affected by the presence of uroliths. The events involved two completely separate and distinct systems, and both cases impacted more than one species of teleost - the first involved a number of rainbow parrotfish (Scarus guacamaia) and a striped burrfish (Chilomycterus schoepfi), and the second involved several scorpionfish (Rhinopias spp.) and leaf scorpionfish (Taenianotus triacanthus). All cases resulted in mortalities. In both events, clinical signs did not manifest until late in the disease process, and in most cases urolithiasis was presumed to be one of a number of chronic factors contributing to mortality. The vast majority of stones analyzed were comprised of calcium phosphate (apatite), though one stone was identified as calcium hydrogen phosphate dihydrate (brushite), and another as potassium hydroxide monohydrate. A number of iatrogenic etiologies for uro- and nephrolithiasis in teleosts have been described, primarily in aquacultured finfish and with limited relevance for smaller group or individualized management of exotic teleosts.^6,7,8 Of the cases describing urolithiasis in animals under managed care in zoos and public aquaria, most are incidental findings, and definitive diagnoses are often further confounded by small population sizes and the inherent difficulties presented in performing routine care on healthy, free-swimming fish.^9,10 In addition to a thorough review of the literature, current clinical diagnostics, treatment techniques, histopathologic results, and environmental parameters from both cases are discussed.

Acknowledgements

The author wishes to thank the husbandry and animal health staff at the Florida Aquarium for their support.

* Presenting author

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