一、鱼的分类鱼类在生物分类上属于动物界、脊索动物门、脊椎动物亚门。鱼类包括三个纲:即圆口钢、软骨鱼纲和硬骨鱼纲。三个纲的种类特征大致如下: (一)圆口纲::是鱼类中较原始种类,海产。其特征:无偶鳍,体鳗形,无鳞,软骨。脊椎骨不发达。无上下颌骨,故口不能启闭,鼻孔只一个。这个纲又可分八目鳗目和盲鳗目。盲鳗目和部分八目鳗目营寄生生活,常从鱼的鳃部钻入鱼体内、或咬穿鱼的体壁钻入体腔,以鱼的肌肉和内脏为营 First, the classification of fish Fish in the taxonomic belong to the animal kingdom, chordata door, vertebrate subphylum. Fish includes three classes: namely round mouth steel, cartilaginous fish and teleost body. Three broad categories of features are as follows: (A) round mouth :: is the more primitive species of fish, seafood. Its characteristics: no fins, eel body, no scales, cartilage. Spine is underdeveloped. No upper and lower jaw, so the mouth can not open and close, only one nostril. This outline can be divided into eight orders eel head and blind eel head. The blind eel head and part of the octagonal eel head camp parasitize the life, often from the gill of fish into the fish body, or bite through the body wall of the fish into the body cavity, the fish muscle and internal organs for the camp