How to Identify Common Blowfish

To identify Common Blowfish (Torquigener pleurogramma), look at these key features.

Physical Characteristics

Body shape

rounded

Coloration

Dorsal surface typically mottled brown, grey, or olive with darker spots and irregular markings, often with a pale or white ventral side. Some individuals may exhibit faint lateral stripes. Coloration can vary slightly depending on habitat and geographic location.

Scale type

none

Mouth position

terminal

Distinctive features

Ability to inflate body into a spherical shape when threatened, Small, spiny dermal denticles covering the body (not always erect), Absence of pelvic fins, Fused teeth forming a beak-like structure, Relatively small eyes set high on the head

Dorsal fin

Single, small, and set far back on the body, typically with 9-11 soft rays.

Tail fin

Truncate to slightly rounded caudal fin.

Pectoral fin

Small, fan-like, positioned laterally behind the gill openings, with 14-17 rays.

Distinctive fins

No pelvic fins. Anal fin is similar in shape and size to the dorsal fin, positioned directly below it, with 7-9 soft rays.

Identification Tips

1. 1

   Body Shape and Inflation

   Observe its characteristic rounded body and its ability to inflate when stressed. This is a primary defense mechanism.

2. 2

   Coloration and Markings

   Look for the mottled brown/grey/olive dorsal coloration with darker spots and a paler belly. The pattern can be a key identifier.

3. 3

   Fin Arrangement

   Note the absence of pelvic fins and the small, posteriorly placed dorsal and anal fins. The caudal fin is typically truncate.

4. 4

   Beak-like Mouth

   The fused teeth forming a strong, beak-like mouth is characteristic of pufferfish and is used for crushing shells.

5. 5

   Sand Circles (specific populations)

   In certain areas, particularly off Amami-Oshima, Japan, the presence of elaborate geometric sand circles on the seafloor is a definitive sign of male Torquigener pleurogramma activity.

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