For a time people took to killing fish with poisonous plants, as evidenced by the warning in the chapter "Wang Zhi" in the book Shunzi not to poison fish during the reproductive season.
當時出現以有毒植物毒魚的風氣，《荀子．王制》有「… … 魚鱉鰍鱣孕別之時，網罟毒藥不入澤，不夭其生，不絕其長也。」