Fish are aquatic vertebrate animals that are typically ectothermic ( previously cold-blooded ) , covered with scales , and equipped with two sets of paired fins and several unpaired fins .
鱼是水生脊椎动物，典型特征是属冷血动物，全身有鳞片，有一对鱼鳍或几个不成对的鱼翅。
Mobile ectothermic animals can control their body temperatures by selecting specific thermal conditions in the environment , but embryos-trapped within an immobile egg and lacking locomotor structures-have been assumed to lack that ability .
