The Early Life History of Invasive Goldfish Carassius Auratus in Tibet, China

The goldfish Carassius aruatus had become one of the worldwide invasive fishes and introduced for aquiculture in Tibet at the early 1990’s. In this study, we validated the daily deposition of increments in otolith of goldfish and used the otolith microstructure to deduce the hatching date and to characterize the early growth of two different populations of goldfish sampled from Tibet in 2011. Two increments were deposited in the lapillus in the newly-hatched larva and the increments were formed daily. Otolith microstructure revealed the hatching dates of the Chabalang population from the valley of Lhasa River and the Chongdui population from Yarlung Zangbo River were started from 4 April and 29 April respectively. Back-calculated spawning times of goldfish population were brought ahead when compared with the native population in the middle of Yangtze River. The standard length was correlated linearly with the otolith radius and the growth rate of Chabalang population was higher than Chongdui population during the larval and juvenile stages. Our results of the spawning time and early growth pattern suggested goldfish had adapted to the plateau environment and established in Tibet.