fT 



The Aquarium 



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Volume II 



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APRIL, 1913 



Number 1 



J 



The Blue Angel Fish. 



JOHN TREADVVELL NICHOLS, New Voik. 



THE most modern, best equipt fish 

 is a short-bodied animal, pointed 

 in front and behind, more or less flatten- 

 ed from side to side, with fins which 

 propel it and direct and check its 

 motion through the water. It has a 

 firm skeleton of bone, and sharp erectile 

 spines on the back and in some of the 

 fins protect it from its neighbors. Its 

 body is covered 

 with thin, plate- 

 like, overlapping 

 scaleswhich 

 a firm 



give 

 face to 



sur- 



press 



the 



against 

 water. 



The blue 

 angel fish is just 

 such a modern 

 species. If we 

 examine some 

 of the many 

 kinds of fishes 

 which swarm in 

 the ponds, 

 streams and seas of the world 

 find that a great part, but 



BLUE ANGEL FISH, Angelichthys ciliaris 



Photograph published by courtesy of the New York Zoological Society 



we will 

 not all, of 

 them come up to this standard. The 

 sharks and dogfish lack the bony 

 skeleton and covering of scales, the 

 dace and goldfish have not the spiny 

 fins and are sometimes pushed to the 

 wall (of the aquarium) by sunfish, which 

 have. 



A study of the past history of fishes, 

 as recorded in those which are preserved 



as fossils in the rocks, shows that the 

 less well equipt kinds came before the 

 better equipt ones and are, in a sense, 

 old fashioned. Old fashioned species 

 are sometimes remarkably tough, how- 

 ever. If a mixed lot of fishes be hauled 

 up in a net from rather deep water, 

 many will lie at the surface dying or 

 helpless, the change in pressure having 

 caused their stomachs to pop out of 

 their mouths, or otherwise damaged 

 them. But the 

 dogfish will 

 squirm and snap 

 on deck, and if 

 thrown over- 

 board, promptly 

 start to swim 

 down again,litlle 

 worse for wear. 

 The zone 

 where most 

 species of fishes 

 are to be found 

 is along the 

 shore. Further 

 down under the 

 depths of the 

 ocean, or out over its surface, or up 

 the rivers into fresh water, there is less 

 variety of fish life. Fishes are also 

 fewer in the colder water toward the 

 poles than along tropical shores where 

 the coral reefs harbor innumerable 

 varieties. It is on these reefs, in the 

 very center of the fish world, that the 

 blue angel fish, Angelichthys ciliaris 

 (ichthys means fish and ciliaris, from a 

 word meaning lash, refers to the gaudy 



Copyright. 1913. by W. A. T'oyt 



