Study on morphological characteristics and hypoxia tolerance of <i>Culter alburnus</i> (♀) × <i>Magalobrama terminalis</i> (♂) and <i>Culter alburnus</i>

C. alburnus (♀) × M. terminalis (♂) ( CM ) is a new national cultivar formed by interspecific hybridization between C. alburnus and M. terminalis. To explore the morphological characteristics and hypoxia tolerance of CM and C. alburnus , quantitative and countable traits were measured for CM and C. alburnus ; then we conducted hypoxia stress research. The results: 1. The main characteristics of CM that differed from C. alburnus in appearance were an increase in body height and thickness, a small blunt pointed head, bulging back of the head, and large scales on the sides of the body. Among the countable traits, the numbers of lateral scales, upper lateral scales, and first-gill rakes of CM were significantly lower than those of C. alburnus , whereas the number of lower lateral scales was significantly greater than that of C. alburnus . 2. At the water temperature of 25 ℃, the DO value of C. alburnus was higher than that of CM . The Superoxide dismutase (SOD) or glutathione (GSH) index of CM increased more when it increased and decreased less when it decreased. The SOD or GSH index of CM was higher than that of the CM under the same hypoxic stress time. Therefore, it was speculated that CM might have stronger hypoxia tolerance than C. alburnus . In summary, CM was generally similar to C. alburnus in terms of morphological characteristics; however, there were differences in body height, body thickness, tail handle, and scales. It has been speculated that CM have a stronger tolerance to hypoxia.