Abstract:
Background: Plants like ‘Derris’ produce rotenone, a potent piscicide. Using rotenone as a
piscicide presents challenges for aquaculture due to its toxicity to a wide range of aquatic life,
potentially harming non-target species and disrupting aquatic ecosystems. An antidote is necessary
to counteract the adverse effects of rotenone on non-target aquatic species.
Objectives: To determine the LC90 (lethal concentration for 90% of the population) value of
Derris plant extract using the brine shrimp assay and to evaluate cow dung as a potential natural
antidote for piscicides poisoning by the Derris plant
Methods: This study utilized aerial parts of Derris plant and cow dung, collected from Southern
province in Sri Lanka. The identity of the Derris plant was confirmed at the National Herbarium
Peradeniya. Plant extraction involved soaking powdered material in acetone and distilled water
(maceration), followed by filtration, rotary evaporation and freeze-drying. The lethality of the
extracts was evaluated using a brine shrimp bioassay, determining the LC90 values. Antidote
activity was tested on cichlid fish (n=20) using different concentrations of cow dung solution (5,
10, and 20 g/L). Potassium permanganate (KMnO4) served as a positive control, used a negative
control (without antidote) and fish mortality was recorded after treatment.
Results: Brine shrimp bioassay revealed that lethal concentrations of water and acetone extracts
of Derris plant aerial parts with LC90 values of 45.1 and 31.4 µg/mL, respectively. Antidote
activity tests using cow dung showed no fish mortality at concentrations of 5, 10, and 20 g/L for
water extract. KMnO4 served as a positive control with no fish mortality. The study identified cow
dung at a concentration of 5 g/L as the most effective antidote.
Conclusions: The results suggest that the potential antidote properties of cow dung against
piscicide (rotenone) toxicity in fish. However, further research is crucial to understanding the
underlying mechanisms and chemical components involved, highlighting its potential for
sustainable aquatic ecosystem management.
