ObjectiveVeterinary care of aquatic species, particularly fish, is limited by a lack of knowledge regarding their unique physiology. Tissue enzyme activities measured in plasma are used for assessing function and potential damage to specific organs and tracking disease progression in live animals. The objective of this study was to identify tissue(s) of origin and plasma concentrations for specific enzymes in healthy Golden Trevally Gnathanodon speciosus. We hypothesized that enzymes would exhibit tissue‐specific tropisms, with higher activities in one or more tissues compared to others.MethodsSix fish were randomly selected from a public aquarium population to obtain antemortem blood samples. The fish were then euthanized, and tissue samples were collected via gross necropsy. Six enzyme activities and two chemical analytes were examined across samples of plasma and 10 tissues from each fish.ResultEnzyme activities exhibited significant organ specificities. Aspartate aminotransferase, lactate dehydrogenase, and creatine kinase levels were highest in skeletal muscle, with variably high levels in gonads. Alkaline phosphatase levels were highest in the kidney, spleen, and liver. Alanine aminotransferase levels had high specificity for the liver. Gamma‐glutamyl transferase was only detectable in the kidney and plasma.ConclusionThis work establishes baseline tissue enzyme origins for Golden Trevally, which will aid clinicians in diagnostic interpretation of blood chemistries and improve veterinary care for this understudied fish species.

OBJECTIVE To establish an echocardiographic technique and 2-dimensional reference parameters for southern stingrays (Hypanus americanus). A second objective was to compare echocardiographic measurements obtained from animals of different sex, size, environment, handling technique, and position. ANIMALS 84 presumed healthy, wild, semiwild, and aquarium-housed southern stingrays. PROCEDURES Animals, anesthetized and manually restrained, were positioned in dorsal recumbency, and echocardiography was performed. A subset of this population was also imaged in ventral recumbency for comparison. RESULTS Echocardiography was feasible, and reference parameters were established for this species. While some standard measurements could not be assessed due to body habitus, all valves, chambers, and the conus were clearly visualized in the majority of animals. Statistical significance was reached for some variables when comparing animals from different environments and handling methods, but these differences were not considered clinically relevant. The data were therefore separated into 2 subsets of echocardiographic reference parameters based on disc width since some of the measurements were dependent on body size. This approach mostly separated the sexes due to strong sexual dimorphism. CLINICAL RELEVANCE Limited information is available regarding cardiac disease in elasmobranchs; most of the available information on cardiac physiology focuses on a few shark species. Two-dimensional echocardiography is a noninvasive tool utilized to evaluate cardiac structure and functionality. Southern stingrays are one of the most commonly displayed elasmobranchs in public aquaria. This article expands on the growing body of information regarding veterinary care in elasmobranchs and provides clinicians and researchers with another diagnostic modality to utilize in screening for health/disease.