Pen and paper.

1. First of all, the profile of this fish is smooth, and its tail looks like a pout. Then, its eyes and pupils are drawn on its head.

2. Draw the fish mouth strip under the eyes, and then draw the line that distinguishes the fish head from the fish body.

3. Then paint the eyes of the fish black, paint the head yellow and draw a blush on it.

Draw pink and yellow dots on the fish's body and tail, and a simple fish will be drawn.