Abstract Objective At the U.S. Geological Survey Leetown Research Laboratory in Kearneysville, West Virginia, an approximately 3-year-old, captive-held Northern Snakehead Channa argus with clinical signs of abdominal distention died and was necropsied 1 day after an examination under anesthesia. A mass discovered in the midcoelomic cavity, presumed to be deformed spleen, was comprised of large, pseudocystic structures that contained considerable volumes of opaque, straw-colored fluid. Methods A histopathological evaluation revealed that the tissue consisted of foci of small capillaries, nodular areas of proliferating, pleomorphic endothelial cells, and areas of necrosis within the pseudocyst wall. Positive nuclear and nonspecific immunolabeling with a vascular marker, cluster of differentiation 31, was concentrated in and around vascular spaces. Result Based on these observations, the tumor has been putatively identified as a hemangioendothelial neoplasm. Conclusion This would represent the first report of a vascular tumor in a Northern Snakehead and, globally, one of the few described neoplasms identified in a member of the Channidae family.