(Ophirides maculata) with the body box shaped the anterior fins are large, long and wide and very active. The tail is drawn tight and are the energy is done by the fins except for quick movements when the tail expands and squirms tightly. The posterior ventral and the dorsal fins also are used for swimming and particularly the latter along with the anterior controls, which here are made of the stiff arches. Fishes of the Angel Fish type also have smaller tails but in them are very active. Further help is had by the dorsal and ventral body extensions which are there and very movable. In fact the entire posterior region flaps and consists in swimming. The box fishes are slow swimmers, the clown of the seas. The most graceful swimmers are the eels, with their long serpentine movements flowing in successive waves from the anterior third to the tip of the tail.