Abstract: An ethological experiment was conducted to study the fast-start swimming performances of juvenile Cyprinus carpio and to explore how the electrical stimulation parameters affect these performances. Four stimulation field strengths (0.25, 0.40, 0.55, and 0.70 v·cm^-1) and five stimulation durations (10, 50, 90, 130, and 170 ms) were installed to measure the fast-start swimming performances of ninety experimental fish with a body length of 6.47 cm ± 0.09 cm and a body weight of 6.36 g ± 0.03 g at water temperature 25.0 ℃±0.5 ℃. When the stimulation field strength raised from 0.25 v·cm^-1 to 0.44 and 0.55 v·cm^-1, the fish’s somersault angle at stage 1 (θ_s1) and the maximum linear acceleration (α_max) and maximum velocity (V_max) at stage 2 all increased significantly (P < 0.05), while a further raise of the field strength had no significant effects on the three parameters (P>0.05). Both the α_max and the V_max increased significantly (P<0.05) with the increase of stimulation duration from 10 to 50 ms, but had less change (P>0.05) with the further increase of the stimulion duration. When the stimulation field strength was 0.55 v·cm^-1 and the stimulation duration was 50 ms, the θ_s1, α_max,and V_max were (56.51 ± 4.11) deg, （31.60 ± 3.62） m·s^-2, and （1.34 ± 0.07） m·s^-1, respectively. This study suggested that the juvenile C. carpio exhibited a ‘fast and straight line’ escape maneuver and had stronger fast-start swimming performances, and there existed threshold values in response to the electrical stimulation parameters.

Key words: Exotic weeds, Invasion, Species interaction, Allelopathy, Chemical mechanism