[pp.127-132]

‹Research Report›Food habits of larval and juvenile Japanese dace (Tribolodon hakonensis) in a river in Ja

Yumi NAKAJIMA, Takuya ITO, Shingo FUJIMOTO, Naoko YOSHIDA and Masahide YUMA （Ryukoku University）

Abstract:
The Japanese dace (Tribolodon hakonensis ) is an indigenous freshwater fish widely distributed in Japan. Although the species is common, its food habits have not been well documented, especially during its larval and juvenile stages. To clarify the food habit of larval and juvenile dace in the natural environment, we sampled fish in the Ado River in Shiga Prefecture, Japan, in four types of habitat: Spur dikes zone, Pool, Backwater, and Plants zone. Analysis of gut contents showed that the ratio of diatoms was highest in the Spur dikes zone. At the other three sites, chironomid larvae were the primary food item. The number of diatom cells in the guts of dace was also largest from the Spur dikes zone. These findings suggest that larval and juvenile dace are omnivorous and possibly adopt an opportunistic feeding strategy depending on the availability of food items in each habitat.

Key Word:
river, food, algae, larval fish, juvenile fish

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