Fish is the oldest vertebrate. The hybridization of some different chromosome numbers [1]_ Twilight Gallery wields the Σ k, and the fiber machinery is fat, from fresh water lakes and rivers to salt water seas and oceans. Fish is a kind of temperature-changing vertebrate that lives in water all year round, breathes through gills and uses fins to assist body balance and movement. According to the statistics of the late Canadian scholars, there are 24,618 species of fish * * * in the world, accounting for more than half of the named vertebrates, and new species of fish are constantly being discovered, with an average of about 15 species per year, which should have increased by more than 1,5 species in more than ten years. At present, there are about 32,1 species of named fish in the world. It is the most primitive and lowest group of vertebrate subphylum.

Fish is rich in animal protein and phosphorus, which is rich in nutrition and delicious, easily digested and absorbed by human body, and plays an important role in the development of human physical strength and intelligence. Other parts of the fish can be made into cod liver oil, fish glue, fish meal, etc. Some fish, such as goldfish and tropical fish, are colorful and have high ornamental value. China has a long coastline and many rivers and lakes, and the species of fish are very rich. According to the survey, there are more than 1, species of freshwater fish in China, and the famous "four major fishes" (herring, grass carp, silver carp and bighead carp), carp and crucian carp are the main excellent freshwater fish species in China. There are about 2, known species of marine fish in China, including hairtail, large yellow croaker and salmon. A complete picture of marine fish

The complete picture of marine fish is as follows:

1. Black-headed fish

The common name is pig-billed fish, and many species live in the water layer over 1m. China is mainly distributed in the Yellow Sea, Bohai Sea, East China Sea and South China Sea.

2. Laobanyu

Laobanyu, whose scientific name is Kunray, has a lot of thorns and no bones. Its meat can be eaten fresh, but it is more pickled and processed into light dried fish. Ray's muscle contains trace urea, so it needs to be scalded with boiling water before cooking fresh food to remove odor.

3. Needle fish

Needle fish is distributed in the western part of the North Pacific Ocean, and it is only found in the Yellow Sea and Bohai Sea in China, mostly concentrated in shallow sea estuaries. Needle fish is rich in nutrition and has high economic value. Needle fish belongs to marine miscellaneous fish. Because of its short growth cycle, rapid generation renewal and easy replenishment of resources, it often maintains a certain catch.

4. Treasure fish

Treasure fish, commonly known as European flounder, has a significantly shortened growth period, which can reach about 5-6 g in the same year under suitable conditions. Under the condition of controlled temperature and light, mature eggs can be obtained all year round, and artificial insemination is used for artificial reproduction.

5. Spanish mackerel

Spanish mackerel is distributed in the western part of the North Pacific Ocean and is found in the Bohai Sea, the Yellow Sea and the East China Sea. In summer and autumn, they migrate in groups, and some of them enter Bohai Sea to lay eggs. In autumn, they often seek bait in groups near coastal islands and rocks, which is one of the northern economic fish. How to draw a picture of a fish

The fish is drawn as follows:

Material preparation: a piece of paper and a black pen.

operation steps:

1. First, draw two arcs on the paper, which are the fish's body, and the two sides don't need to be closed. Select the opening position on one side and draw two close ellipses, which will become the fish's mouth. Note that this mouth is round and flat.

2. Then draw an arc in the longitudinal direction on the quarter of the whole body near the fish mouth, and draw the fish eye with a circle between the arc and the mouth, thus completing the painting of the fish head. Pay attention to the fish's eyes and don't leave white eyes.

3. Draw the fish's tail directly from the open end on the other side. The shape of the tail should be enlarged appropriately, and at the same time draw the fish's tail with a curve, which gives people a sense of suspension of the fish in the water.

4. The dorsal fin and pectoral fin are also drawn with curves, which makes the image of fish more like swimming in the water. Use curves and lines to describe the dynamics of fish.

5. Finally, complete each connecting part, and check the proportion of each part and whether the fish tail is symmetrical up and down.

Key points of painting:

1. Start with decorative painting. Picture segmentation, point, line and plane composition, visual balance, and rhythm of picture element arrangement. Color collocation, color distribution and so on, color psychology. Starting from the most basic law of learning visual aesthetic feeling, it will be of great help to art learning at any stage in the future.

2. Then sketch painting begins to learn. Learn structure sketch first, and use lines to express structural relations and spatial perspective relations. From simple geometric shape to complex geometric shape, to plaster head and still life sketch. Learn how to brush and draw smooth lines. The purpose is to learn to express the spatial structure of objects.

3. Learn the color composition and usage rules through still life and landscape sketch, which echoes the color collocation and distribution in plane composition. How to use color contrast to shape the volume of light and shadow, the performance of different materials under different light sources, and color psychology.