The approved use of oxytetracycline (OTC) in U.S. aquaculture is limited to 
specific diseases in salmonids and channel catfish. Oxytetracycline may also be 
effective in controlling diseases in other fish species important to public 
aquaculture, but before the approved use of OTC can be augmented, an analytical 
method for OTC in fillet tissue from multiple species of fish will be required 
to support residue depletion studies. The objective of this study was to develop 
and validate a high performance liquid chromatography (LC) method that is 
accurate, precise, and sensitive for OTC in edible fillets from multiple species 
of fish.
Homogenized fillet tissue from walleye, Atlantic salmon, striped bass, white 
sturgeon, rainbow trout, and channel catfish was fortified with OTC at nominal 
concentrations of 10, 20, 100, 1000, and 5000 ng/g. In the tissues fortified 
with OTC at 100, 1000, and 5000 ng g, the mean method recovery ranged from 83 % 
to 90 % and the RSD ranged from 0.9 % to 5.8 %. In all other tissues, the mean 
method recovery ranged from 59 % to 98 % and the RSD ranged from 3.3 % to 20 %. 
Method quantitation limits ranged from 6 ng/g to 22 ng/g for the six species. 
The LC parameters produced easily integratable OTC peaks without co-elution of 
endogenous compounds. Nineteen chemicals used in aquaculture were evaluated for 
potential chromatographic interference and only one chemical illegal for use in 
the U.S., sulfadimethoxine, showed potential for interference. The method is 
accurate, precise, and sensitive for OTC in fillet tissue from six species of 
fish from five phylogenetically diverse groups.