①Patten zone overlap with pectoral fin
Best indicator to identify Bullet tuna and Frigate tuna is to observe if the pattern zone the dorsal side overlap with the pectoral fin.
No overlap = Bullet tuna
Overlap = Frigate tuna
Photo below show the exmple of a real fish.
②Shape of the scale coverage
Another good indicator to identify Bullet tuna and Frigate tuna is to observe shape of the scale coverage zone on the leteral side.
Scale coverage becomes narrow toward the caudal fin = Bullet tuna
Scale coverage becomes narrow before the 2nd dorsal fin = Frigate tuna
Photo below show the exmple of a real fish.
③Conectivity of the opercular pigment
Opercular pigment conectivity to the dorsal pigment area is another indicator to identify Bullet tuna and Frigate tuna. Note that the opercular pigment could be damaged during the fishing process or handling process.
Connected = Bullet tuna
Isolated = Frigate tuna
Photo below show the exmple of a real fish.
