Many Mekong ? sh species spawn in Cambodia at the beginning of the annual ? ood, after which their fry drift down the Mekong and its tributary rivers into the Mekong Delta. During the ? ood, ? sh fry move from the main rivers to ? ooded areas where they can feed and grow, and as ? ood levels fall they move back to the main river systems. Pangasiid cat? sh are a particularly important component of the fry drift, as they were the target of a large stationary bagnet (Dai) ? shery along the Mekong and Bassac Rivers in Cambodia and Viet Nam. The fry were sold to aquaculturists, but the ? shery was outlawed in Viet Nam in 2000 when fry from hatcheries became available.