February 15-18, 2009 Washington State Convention Center Seattle ...

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ACUTE TOXICITY OF 5% PRENTOX® PRENFISH ROTENONE TO FRESHWATER
PRAWN Macrobrachium rosenbergii
Tiffany Ogunsanya*, Robert Durborow, Carl Webster, James Tidwell, Hank Jarboe, Changzheng Wang,
Lingyu Huang and Yolanda Brady
Aquaculture Research Center
Kentucky State University
Frankfort, KY 40601 USA
Tiffany.Ogusnanya@kysu.edu
Predator fish, such as bluegill Lepomis macrochirus and green sunfish Lepomis cyanellus, are notorious for preying on juvenile
prawn Macrobrachium rosenbergii. Before the prawns are stocked, ponds are often drained in an attempt to kill “trash” fish
species; however, some species survive. Rotenone is one of the most frequently used piscicides to eradicate bluegill and green
sunfish. However, there is no data regarding the concentration of rotenone that is lethal to the prawns.
The primary goal of this study was to evaluate the acute toxicity of rotenone on juvenile freshwater prawns and to provide toxicity
data that is applicable for prawn farmers. The mortality response of juvenile prawns exposed to different rotenone concentrations
was evaluated during two 96-hour bioassay experiments to determine the LC50 values. For trial 1, freshwater prawns
were exposed to the following Prentox® Prenfish rotenone treatments; 0.0 mg/L, 1.0 mg/L (0.05 mg/L active ingredient),
3.0 mg/L (0.15 mg/L active ingredient), 5.0 mg/L (0.25 mg/L active ingredient), and 10.0 mg/L (0.50 mg/L active ingredient),
respectively. In the second 96-hour bioassay, M. rosenbergii were exposed to treatments of Prentox® Prenfish ranging from
0.0 mg/L, 2.2 mg/L (0.11 mg/L active ingredient), 3.6 mg/L (0.18 mg/L active ingredient), 6.0 mg/L (0.30 mg/L active ingredient),
10.0 mg/L (0.50 mg/L active ingredient), and 16.7 mg/L (0.84 mg/L active ingredient), respectively.
Results from trial 1 showed that juvenile prawns were able to achieve 100% survival when exposed to Prentox® Prenfish
rotenone concentrations of 1.0 and 3.0 mg/L, while mortalities did occur at the 5.0 and 10.0 mg/L treatments (Table 1). Results
from this study provide new insights on rotenone tolerances in juvenile freshwater prawns and may improve the culture
practices for this species.
Table 1. Survival of juvenile prawns during the 96-h toxicity Trial 1.
Prentox® Prenfish
rotenone treatment
Number of prawns per treatment Survival of prawn
1.0 mg/L (0.05 AI) 24 100%
3.0 mg/L (0.15 AI) 24 100%
5.0 mg/L (0.25 AI) 24 54%
10.0 mg/L (0.50 AI) 24 21%