FOOD SELECTION AND GROWTH OF YOUNG SNAKEHEAD CHANNA-STRIATUS

Food selection and growth of young snakehead Channa striatus were stud ied in the laboratory and in a field trial. In the laboratory, first-f eeding snakehead larvae of 6-7 mm total length (TL) with a mouth openi ng of 0.55 mm selected for Artemia nauplii, and against formulated fee d. Fish began feeding on formulated feed at 12 mm TL when their mouth width reached 1.0 mm. In both laboratory and freld trials, snakehead d iets changed as fish size increased. For fish 15-20 mm TL, cladocerans and copepods were 96.5% of their diet. With fish 30-40 mm TL, zooplan kton consumption was greatly reduced while benthic organism consumptio n increased. Fish 45-50 mm TL fed exclusively on benthic invertebrates . Diet shift from zooplankton to benthic invertebrates was not due to reduced zooplankton availability, but was instead related to changes i n gill raker structure. Low density of benthic invertebrates in the fi eld trial caused reduced fish growth rates when fish switched diets fr om zooplankton to benthos. Our results indicate that snakehead can lak e Artemia nauplii as a larval starter food, then accept formulated fee d at greater than or equal to 12 mm TL. Zooplankton can serve as food for snakehead < 40 mm, but formulated feed should be provided for larg er fish which are unable to catch zooplankton.