How to Identify Japanese dace

To identify Japanese dace (Tribolodon hakonensis), look at these key features.

Physical Characteristics

Body shape

elongated

Coloration

Dorsal side is typically dark olive to brownish-gray, fading to silvery-white on the ventral side. Fins are often dusky, sometimes with reddish tints, especially during spawning season. A faint lateral line may be visible. Coloration can be highly variable depending on habitat (e.g., darker in clear, rocky streams, lighter in turbid or estuarine waters).

Scale type

cycloid

Mouth position

terminal

Distinctive features

Relatively large scales (55-65 in lateral line), Three rows of pharyngeal teeth (5.3.2-2.3.5), Small barbels sometimes present at the corners of the mouth, though often absent or rudimentary, Terminal mouth

Dorsal fin

Single dorsal fin, typically with 3 unbranched and 7-8 branched rays. Origin usually slightly posterior to the pelvic fin origin.

Tail fin

Forked caudal fin, moderately emarginate.

Pectoral fin

Pectoral fins are relatively short, with 15-17 rays.

Distinctive fins

Anal fin with 3 unbranched and 7-9 branched rays. Pelvic fins with 1 unbranched and 8 branched rays.

Identification Tips

1. 1

   Scale Count

   Count the number of scales along the lateral line (55-65 scales). This is a key distinguishing feature from other Tribolodon species.

2. 2

   Pharyngeal Teeth

   Examination of the pharyngeal teeth (5.3.2-2.3.5 formula) is definitive but requires dissection.

3. 3

   Body Shape and Coloration

   Elongated body, dark dorsal, silvery ventral. Look for reddish tints on fins, especially during breeding season. Note the absence or rudimentary nature of barbels.

4. 4

   Habitat

   Its presence in both freshwater and brackish environments within its known geographic range is a strong indicator.

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