The Swimming Champion?

　　Because fish lives in multivariate habitats in water, after millions years of evolution, they developed into animals with all kinds of body structures and living habits. These structures and living habits become a three in one phenomenon, which gathers environment, function and adaptation together. Therefore, many funny stories are deducted from them. So far as the body structure of fish is concerned, they are mainly divided into four types according to their shapes, which determine their ability for swimming: 1. Spindle-shaped fish: this is the most commonly seen body shape of fish. The overall fish has a streamlined structure, which can reduce resistance during swimming. The champions of swimming among all fish are found in them, such as carps and grass carps. 2. Fish with flat-sides. The axis of this kind of fish from left to right is relatively short, while the axis from its belly to its back increases relatively. Their ability in swimming is not so good as those spindle-shaped fish. Fish with flat-sides include mullets and blunt-snout bream etc. 3. Fish of flat-shaped. This kind of fish is dorsoventrally compressed. They live in the bottom of the waters. They move slowly and their ability in swimming is poor, such as skates, angler, Pseudecheneis, Hillstream loach and so on. 4. Stick-like fish. This kind of fish has long and stick-like body shape. They have small heads and thin tails. The axis from their heads to their tails is the longest. The axis from their left to their right and from their belly to their back is all very short. The section of their body is like an oval, such as finless eel, eel, and mastacembelus aculeatus. This kind of fish is used to live in caves and they often sneak into the mud or sands in the bottom of water. They move like snakes. Besides, some other fish have special body shapes: such as the shape of ribbon, balls, boxes, mola, flier, arrow shape, and unsymmetrical shapes etc.