Description: The body of the bigeye tuna is cigar-shaped (tapered at both ends). The head is pointed and the eye is relatively large. The color is dark metallic brownish blue to dark yellow on the back becoming gray or whitish below. There often is a bluish stripe on the side. In most individuals, the length of the pectoral fins should enable one to identify the species properly. Both bigeye and yellowfin tuna look similar, but bigeye tuna have pectoral fins which extend well past their anal fin, while yellowfin tuna have much shorter pectoral fins. Tuna which cannot be distinguished by external characteristics can be positively identified by liver characteristics. Bigeye tuna livers are striated (covered with blood vessels) along the trailing edges, while yellowfin tuna livers are smooth. Small bigeye tuna also may be distinguished from albacore by the characteristics of the liver. The liver is heavily striated in the albacore while the bigeye tuna liver is only striated along the trailing edges.