First describe what a goldfish tail looks like, and then describe why. First, describe the tail of the goldfish like a dancing fan or a trembling skirt, and then describe the reason. For example, the tail of a goldfish is very big and soft, and it sparkles in the sun with dazzling colors. When the goldfish swims or turns, its tail will sway constantly. Its soft and waxy tail is like a fan that dances at any time during a square dance, or like a girl's trembling skirt.