Fish Swimming
 Fish swim by exerting force against the surrounding water. There are exceptions, but this is usually done by the fish contracting muscles on either side of its body in order to generate waves of flexion that travel the length of the body from nose to tail, generally getting larger as they go along. However, there are also species which move mainly using their median and paired fins. The latter group profits from the gained manoeuvrability that is needed when living in coral reefs for example. Breder C.M. 2003.