Changes in body color: The color of goldfish is mainly produced by many pigment skin cells in dermis. There are only three color components of goldfish: black pigment cells, orange pigment cells and light blue reflective tissue. All these ingredients exist in wild crucian carp. The bright and changeable body color of domestic goldfish is only caused by the recombination and distribution of these three components, the change of intensity and density, or the disappearance of one, two or three of them. Variation of head type: Breeders in China divide head types into tiger head, lion head, goose head, tall head, hat and toad head. Some of them belong to the same type and have different names in different places. For example, breeders in Beijing call it a tiger head, while in the south it is called a lion head; What is called a hat in Beijing is called a high head or a goose head in the south. According to Professor Marco's name, there are three types of head shapes: flat head, goose head and lion head. 1, flat head type: its head skin is thin and smooth, which is called flat head type. There are narrow flat heads and wide flat heads. 2, goose head type: the sarcoma on the top of the head is thick and convex, while the gills on both sides are thin and smooth. 3, lion head type: the sarcoma on both sides of the head and cheeks is a thick lump, which can even cover the eyes when developed. Variant eyes: can be divided into normal eyes.

, longan, eye and blister eye. 1, normal eyes: eyes with the same size as those of wild crucian carp are called normal eyes. 2. Longan: the eyeball is excessively enlarged, and part of it protrudes from the orbit. This kind of eye is called longan. 3. Eye of the sky: Eye of the sky is similar to longan, both of which are larger than normal eyes, and the eyeball also partially protrudes out of the orbit. The difference is that the pupil of the celestial eye turns 90 degrees upward and faces the sky. There is also an eye with translucent bubbles outside the eye, which is called the eye. 4. Blister eye: The eye socket of this eye is as big as longan, but the eyeball is as small as normal eyes, and there are translucent bubbles on the outside of the eyeball. This kind of eye is called bleb eye. There is also a kind of eye similar to blister, except that the translucent blister in the orbit is smaller, and only a small protrusion is formed in the abdomen of the orbit, which looks like the head shape of a frog on the surface, so it is called frog head, and some people call it toad head. In fact, the types of creatures are not immutable. It can gradually evolve from a simple type to many forms. Feed type of goldfish Although goldfish is an omnivorous fish completely domesticated by human beings, it is the same as other fish such as crucian carp. Whether the feed selection is reasonable and the feeding is correct can directly affect the growth and development of goldfish, the brightness of color, the appearance of traits, the fullness, the number of eggs laid, the hatching rate and the disease resistance of goldfish. Therefore, the feed for goldfish must be rich in protein, fat, carbohydrates, vitamins and a certain amount of inorganic salts and trace elements. For example, if all other conditions are the same, those who can feed enough fresh and live red worms every day will have great growth and development, especially the features like lion head and blisters (referring to sarcoma and blisters), which may be the reason why red worms contain a lot of animal protein, fat, carbohydrates and other rich nutrients.