A female, sunset, thick-lipped gourami (Colisa labiosa) that weighed 8 g and was 5.4 cm from the snout to the end of the vertebral column was examined because of a 5-mm-diameter, midventrally located mass that had developed suddenly 1 month earlier. Cytologic examination of a sample obtained by use of fine-needle aspiration, survey radiography, positive-contrast radiography of the gastrointestinal tract, and Doppler ultrasonography were performed to evaluate the mass. These procedures were not able to provide a definitive diagnosis, but did facilitate surgical planning. The mass was excised, and the abdominal musculature was repaired, using microsurgical techniques. Redevelopment of the mass was not detected during the 5-month period after surgery. Histologic evaluation of the mass revealed an organized hematoma of undetermined cause. Successful manage ment of this gourami illustrated that size should not be a deterrent to diagnostic evaluation and surgical intervention in diminutive fish.
