12.— OBSERVATIONS ON THE HATCHING OF THE YELLOW PERCH. 
BY S. G. WORTH, 
Superintendent of Central Station. 
In the month of March, 1889, a number of yellow perch (Perea flavescens) spawned 
in the aquaria at Central Station, and with but very slight attention quite a number 
of fry were produced. At my suggestion the parent fish had been procured, in the 
absence of better specimens, to replenish the stock of aquarium fish in anticipation 
of the throng of visitors at the inauguration ceremonies. 
The following year it seemed desirable, in view of possible future wants, to under- 
take such a systematic series of observations as would furnish full records of the 
main conditions under which favorable results could be secured; for, however remote 
the necessity of applying the methods of artificial propagation to this abundant 
species, the marked simplicity of the spawning habits of the yellow perch seemed 
alone sufficient to arrest the attention of fish-cultural investigators. Accordingly, 
with the Commissioner’s sanction, 243 ordinary- sized specimens were bought from 
fishermen at Fort Washington, Maryland, and on February 7, 1890, were conveyed to 
the tanks at Central Station. 
The outlay incident to this study was so in considerable, in view of the data obtained 
and the practical release of nearly a million fry, that the cost should be mentioned. 
The purchase price of the adult fish, together with the freights and fares incurred in 
their transfer (that is, all items), amounted to but 115.80. 
On the 21st of February 236 specimens, surviving the bruises received in cap- 
ture, were about equally divided into four glass collector- aquaria of running water, 
the contents of each aquarium being about thirty-five gallons. Apparently there 
were 130 females, and these were placed in the aquaria along with about an equal 
number of males. The water supply was from the city pipes, i. e., from the Potomac, 
and was then at 44° F. Subsequent changes in temperature are noted farther on, 
under the table of egg-production. 
Thus confined, with but little more water space than a half gallon to each speci- 
men, the parent fish remained from this date throughout the spawning period and 
here dropped their eggs. Spawning commenced March 10 and ended April 3, eggs 
being dropped on eighteen days between dates. Nearly all of the eggs were deposited 
during the night or early in the morning and as soon as observed through the glass 
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