MANUAL OF FISH-CULTURE. 155 



was lidded to from day to day for nearly a week, wlieu it was brought 

 up to 1.018, or the same specific gravity as the water used in the marine 

 aquaria. At the time these were placed in the brackish water others 

 were put into fresh-water aquaria, but the latter died within three 

 days. Those in salt water began in two or three days to take food, 

 consisting of chopped oysters, clams, and beef, the jireference being 

 for oysters. At first they would take food only when it was sinking, 

 later they began taking it oft' plants where it had lodged, and finally 

 from the bottom. Nearly all remained healthy, plump, and active for 

 six months, some living until about midsummer. 



For ten years x^ast two or three million shad fry have been reared 

 annually at the Fish Ponds, Washington, D. C. A 6-acre pond is used, 

 the water supply being taken from the city water-works. The dejith 

 varies from 2 to 3 feet, and throughout the whole extent there is a dense 

 growth of water-plants, among which crustacean food multiplies — new 

 supplies being brought in from the water-pipes. Fingerling shad are 

 so tender that the numbers annually liberated can not be ascertained; 

 they can not withstand the handling consequent upon counting them, 

 not even undergoing transfer in dippers of water, and their scales drop 

 off" on being touched; consequently at high tide they are liberated into 

 the Potomac through a sluice-gate with an outlet pipe about 2 feet in 

 diameter. They require some days to make their escape. By conserva- 

 tive estimate 50 to 60 per cent are held safely until about October. 



Eearing has been experimentally tested at Wytheville and Neosho 

 with good results. At Neosho on the 3d of June, 1892, 700,000 fry were 

 received from Gloucester, N. J.; their growth was satisfactory. In 

 preparing for their release the hatchery branch was cleared of shoals, 

 drifts, and aquatic plants for three-quarters of a mile, and early in 

 November, when the branch was swollen with rain water, 200,000 

 G-months-old fish were allowed to pass through open gates ; they were 

 some hours in escaping, in a continuous silvery mass. These were the 

 first fingerling shad planted in waters tributary to the Gulf of Mexico. 



TRANSPORTATION. 



Good, healthy fry will pass from the jar to the collector-tank as fast 

 as hatched, and unless too thick will not lie on the bottom of the tank, 

 although they sometimes crowd on the side nearest the strongest rays 

 of light. As many as 500,000 to 800,000 are collected in each tank. 

 In transporting, they must be kept in vessels with smooth surfaces, 

 preferably tin-lined cans. Zinc vessels are destructive, and galvanized 

 cans are not recommended. 



About 2,000 to 3,000 fry are put to a gallon of water, which must be 

 pure enough for ordinary drinking purposes and well aerated. The 

 water in the cans must be kept at 58° to 05°, though in rivers and 

 ponds the fry endure a temperature of 90° F. 



As early as 1871, experiments were carried on to retard the develo]> 

 ment of eggs, in order to i^rovide a longer period between the deliver.v 



