Fish Anatomy

Anatomy of a Fish

• Snout: The mouth. The snout length is the space between the eye and the tip of the mouth.
• Preopercle: The bones on either side of the head before the gills.
• Opercle/Operculum: The gill coverings.
• Nape: The ‘neck’ of the fish.
• Shoulder: After the neck.
• Dorsal Fin: The top fin is the dorsal fin; it is located on the fish’s back. When the fish has more than one dorsal fin, the fin behind the first dorsal fin would be the second dorsal fin, etc.
• Dorsal Area: Top part of the fish, under the dorsal fin.
• Lateral Line: The long line running the length of the fish on the sides is the Lateral Line, and can be curved or straight, or entirely gone, depending on the variety of fish. It’s actually a sensory organ that helps the fish detect vibration and movement in the water.
• Caudal Fin: The tail fin of the fish.
• Base of the Caudal Fin: Area before the caudal fin.
• Anal Fin: The bottom back fin behind the anus of the fish which helps with stabilization.
• Ventral Fin: The bottom fin.
• Ventral Area: is the actual abdomen or belly part (or lower half) of the fish.
• Pectoral Fins: The fins on either side of the fish’s body.
• Caudal Keel: These come in pairs on opposite side of the fish, and help with stability. Keels are only on fast swimming fish.
• Finlets: Small fins between the dorsal and caudal fins, and between the anal and caudal fins.