In response to such variable conditions, many freshwater fishes have developed secondary respiratory organs. They use labyrinths, their mouth cavity or their skin as additional breathing surfaces, to overcome the dangers of drought.
在變動多端的環境下，不少淡水魚都發展出第二呼吸器，藉由迷器、口腔、或皮膚增加呼吸表面積，克服乾旱危機。