Ngo Thi Thu Thao * , Dang Thi Thuy An and Tran Thi Ngoc Hanh

* Correspondence: Ngo Thi Thu Thao (email:

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This study was conducted to determine the effects of different pH values on the flocculation efficiency of chitosan and using flocculated algae as diet for nursing sweet snail larvae. In 1st experiment, Chaetoceros algae were flocculated by chitosan at three pH levels: 1).Control (maintaining at pH=9.0); 2). Adjust to 7.0 and 3). Adjust to 5.0. In 2nd experiment, flocculated algae were stored at temperature of 4oC in 15 days to determine the viability and ability to growth after re-inoculation. In 3rd experiment, flocculated algae were used for feeding sweet snail larvae in 20 days. Algae flocculation reached the highest efficiency (91%) after 4 hours at pH 5.0. At control pH treatment (pH 9.0) Chaetoceros obtained highest cell viability (52.23%). After re-inoculation at initial density of 500,000 cells/mL, the highest cell density was obtained at day 15 in pH 7 (8,750,000cells/mL). After 20 days feeding with different flocculated Chaetoceros, the sweet snail larvae in control pH obtained not only highest survival rate (72.52%) but also the highest shell length and height (1938.89 and 1041.67µm, respectively). Our findings indicated that it was necessary to remain pH value from 7.0-9.0 in order to obtain the high algal cell viability after flocculation with chitosan and effectiveness for using as diet for sweet snail larvae.
Keywords: Babylonia areolata larvae, cell viability, Chaetoceros, chitosan, flocculation

Article Details


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