REPORT OF COMMISSIONER OF FISH AND FISHERIES. LXI 



Aquaria at Centrat, Statiox, Washixgton, D. C. (L. G. Harron, in charge). 



Duriug" this year the aquaria were under the charge of Mr. L. G. 

 Harron, who assumed the duty in July, 1891. The aquaria and grotto 

 were thoroughly repaired, and wire-screen covers were made for each 

 aquarium to prevent the escape of specimens and the entrance of any 

 natural enemies. 



In the marine aquaria two-thirds of the water used was artificial, 

 being prepared from Turks Island salt. The balance was natural sea 

 water, the supply of which was obtained from Chesapeake Bay, in the 

 vicinity of Old Point Comfort, Va., and brought to the aquaria with 

 the collections secured at that place. The density of water maintained 

 during the year was from 17 to 19, the aim being to keep it at 18, that 

 of the previous year having been 20 to 22. This reduction resulted in 

 greater success in the carrying of the more delicate specimens, both 

 animal and vegetable. For the aeration of the water, dependence was 

 had on the reduced glass jets. Tlie greatest trouble in tlie manage- 

 ment of the aquaria is the regulation of temperature. In the winter it 

 was held between 50° and 00°, which was satisfactory, by attaching a 

 steani drum to the supply pipe; in the summer, however, no economical 

 method for keeping a suitable temperature was discovered, and as a 

 consequence the maintenance of the aquaria duriug that season was 

 practically abandoned. 



The collections were obtained mainly at Old Point Comfort, Va. 

 Instead of detailing our own launches to this work, as in former years, 

 involving much time and ex])ense, arrangements were made with a 

 local agent, by whom specimens were gathered and placed in live cars. 

 As soon as a sufficient quantity was secured advice was sent to Wash- 

 ington and a messenger was directed to proceed by the Norfolk and 

 Washington steamers for themv By this way the collections were 

 received at the aquaria in twelve to twenty-four hours after being taken 

 from the live cars and at a very slight expense. Collections were also 

 received from the Woods Holl Station. 



About 250 young shad, the product of fry artificially hatched at 

 Central Station and placed in fish ponds, Monument Lot, on the 2Cth 

 of the preceding April, were received October 21, 1891. These fish were 

 about five months old and 2 to 3 inches long. At first they were put in 

 brackish water having a density of 1.005, which was increased from day 

 to day for about six days, when it was brought up to 1.018, the general 

 density of the water used in the marine aquaria. At the time these 

 were placed in the brackish water others were placed in fresh water, 

 but all of the latter died within three days. The former, however, 

 began to take food, consisting of chopped oysters, clams, and beef — 

 the preference being for the oysters — in from two to three days. At 

 first they would not take the food from the bottom but would catch it 

 while falling in the water. Later on, however, they began taking it 

 oft" the plants where it had lodged, and finally from the bottom. Nearly 



