The public aquaeium 260 



Six of the floor pools in the New York Aquarium are oval in shape, 

 28 feet long by 3 feet deep. They are sunk in the floor about one- 

 fourth their depth. A circular pool 38 feet in diameter and 7 feet 

 deep has been used for porpoises. The floor pools, containing seals, 

 crocodilians, fresh-water turtles, or other animals that often leave 

 the water, are provided with sloping platforms, which they can 

 ascend at will. Sea turtles in the New York Aquarium never 

 attempted to leave the water, although kept for years in a pool with 

 a sloping platform. 



The length of life of seals and porpoises in captivity might be 

 greater could they be provided with sea water of normal ocean 

 density. In the New York Aquarium these animals from necessity 

 have been kept in filtered water of low salinity pumped from the 

 harbor. Being heavy feeders that deposit considerable waste matter, 

 the water supply must obviously be separate from that of the more 

 delicate organisms that require absolutely pure water. It is prob- 

 able that seals, porpoises, and manatees could be kept many years if 

 aquariums were provided with outdoor pools to which they could 

 be removed in summer. This should serve to renew their vitality 

 for the trying winter life indoors. 



FISH HATCHERY 



An interesting and instructive exhibit for a public aquarium can 

 be made with a small equipment of jars and troughs for the hatching 

 of fish eggs. The methods employed in national and State fish hatch- 

 eries can be shown with little difficulty, and the equipment can be con- 

 densed to occupy but little space. The fish-hatching jars and troughs 

 in the New York Aquarium are carried on the broad stone coping of 

 one of the floor pools. As the eggs of fishes can be secured from early 

 spring until late in the autumn, it is possible to show fish eggs and 

 young fry in various stages of development and growth during most 

 months of thej^ear. The eggs of trout can be stripped from large 

 fishes in the exhibition tanks. Yellow perch deposit their masses of 

 eggs in the tanks, and these, when fertile, are shifted easily to the 

 hatching jars. The eggs of several kinds of food fishes can be 

 secured from State or national fish hatcheries by making special 

 arrangements. The eggs of whitefish, pike perch, yellow perch, 

 shad, and other species, which should be kept in motion while hatch- 

 ing, require hatching jars of glass; those of trout and salmon are 

 placed on wire trays suspended near the surface in narrow wooden 

 troughs. Hatching troughs for exhibition purposes need not be 

 large or numerous, as in fish-hatchery buildings. Those used in the 

 New York Aquarium are 5I/2 feet long, 1 foot wide, and 6 inches 

 deep. It is customary to paint such troughs inside and out with 

 black asphaltum paint, which is not only a protection against decay 

 but renders them sanitary. For aquarium purposes they may be 

 painted inside with white enamel to make the eggs or young fish 

 more easily visible. The shallow trays bearing the eggs are inserted 

 temporarily until all eggs are hatched. They are merely wooden 

 frames with wire bottoms, measuring a little less than 12 inches 

 square. They are held in position near the surface by small wedges 

 of wood. A constant flow of water through the hatching troughs is 



