尾鳍

Specifically, a halfmoon betta must have a caudal where both ends are exactly180 degrees apart or more, spreading towards the front.

具体来说，半月斗鱼一定要具备开展朝向前方，180°上尾。

Most fishes have unstriated rays along the anterior part of the dorsal and ventral edges (leading edges) of the caudal fin.

在大多数鱼类尾，沿著背与腹前部具有无痕。在一些鱼中，例如鰕虎鱼其有痕与无纹软数量比在鑑定上是有帮助。