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United States Department of Agriculture

Agricultural Research Service

Research Project: Management of Off-flavors and Undesirable Bacteria in Aquaculture

Location: Natural Products Utilization Research

Title: Biofloc technology production systems reduce common preharvest off-flavors in channel catfish

Authors
item Schrader, Kevin
item Green, Bartholomew
item Perschbacher, Peter -

Submitted to: Global Aquaculture Advocate
Publication Type: Trade Journal
Publication Acceptance Date: January 12, 2013
Publication Date: March 15, 2013
Citation: Schrader, K., Green, B.W., Perschbacher, P.W. 2013. Biofloc technology production systems reduce common preharvest off-flavors in channel catfish. Global Aquaculture Advocate. 16(2);74-76.

Technical Abstract: The use of biofloc technology production systems continues to increase in the aquaculture industry worldwide. Studies have not previously been performed to determine the composition of phytoplankton communities and related off-flavor problems in these biofloc production systems. In two separate studies conducted one year apart, composite water samples were collected biweekly during the 2010 study and monthly during the 2011 study. At the end of each study, five catfish were randomly selected for analysis from each of nine 18.6 m2 biofloc culture tanks. Water and fillet samples were analyzed for levels of the common off-flavor compounds geosmin and 2-methylisoborneol. The composition of phytoplankton communities in each culture tank was monitored by microscopy. In addition, water and biofloc samples were evaluated to assess the microbial sources of geosmin and 2-methylisoborneol within the culture tanks. Communities of phytoplankton (including algae and cyanobacteria attached to bioflocs) that developed in the culture tanks were dominated by fast-growing, unicellular and small colonial types of green algae (chlorophytes) and diatoms (bacillariophytes) and slower growing, small colonial types of cyanobacteria (cyanophytes). Although geosmin and 2-methylisoborneol were present in the culture water of each tank during most of the study, levels were typically low and only one tank yielded catfish with geosmin and 2-methylisoborneol in their flesh at levels high enough to be designated as off-flavor. The microbial sources responsible for the production of geosmin and 2-methylisoborneol in the culture tanks remain unknown.

Last Modified: 10/30/2014
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