REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



27 



Another attempt was made to hatch pike-perch eggs shipped by- 

 express from Putin-Bay Station, but two consignme«ts, amounting 

 to 2,000,000, were lost en route. 



A rubber holder for air-liberator plugs was designed by the superin- 

 tendent during the fall of 1894, and in February arrangements were 

 made to have a number of them manufactured. Tliis holder is made 

 of hard rubber and can be used in either salt or fresh water. It is 

 especially adapted for aerating aquaria and the tanks on the cars; 

 it may also prove valuable for hatching floating eggs. 



Aquaria, Central Station (L. G. Harron, Superintendent). 



The defective imitation rockwork in the marine annex was removed 

 early in the summer and replaced by galvanized metal, representing 

 rock face. New rubber tubing and a new filter for the salt-water tanks 

 were put in during the month of August, and a new fresh-water filter 

 was jiurchased in December. This afibrds double the amount of water 

 filtered by the old one. During the winter the salt water was kept at 

 a temperature of from 50° to 56° by means of a steam drum 3 feet 

 long, 6 inches in diameter, containing 9 feet of coiled 1-inch piping. 

 With an average pressure of 25i30unds j^er square inch, the water was 

 passed through the pipe at the rate of 350 gallons per hour. 



On October 16 200 young shad, about 5 months old and from 2 to 3 

 inches long, were received from the fish ponds and were i)ut in brackish 

 water, the density of which was gradually increased to 1.020. They 

 were fed on chopped oysters and were apparently healthy until the 

 middle of January, when they were attacked by disease and 75 of them 

 died. Canned roe was then substituted as food, and within two or 

 three days the mortality ceased and the fish became healthy again. 



Most of the marine specimens in the aquarium during the year were 

 collected by the steamer Fish Hawlc off Cape Charles in October, and 

 at Old Point, Va., by the superintendent. 



On February 13 a goldfish, which had been held for more than a year 

 in a balance aquarium, spawned and about 100 of the eggs were placed 

 in a McDonald jar, the temperature of the water being kept at G8. 

 Ninety per cent of the eggs hatched and about 20 of the young fish are 

 now alive and beginning to color. In June a 2-year-old i^aradise fish 

 spawned in a balance aquarium, and the young are now on hand. 



The fresh-water fishes in the aquarium suffered heavy losses in May 

 on account of the high temperature of the water, and all of the brook 

 trout and yearling landlocked salmon were lost. The temperature of 

 the salt water from October, 1S94, to June, 1895, was as follows : 



