252 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
small spout or spriukliiig pot, they are closely picked over, removing all dead and 
unfertilized eggs, wliicli Avill nearly all turn -vrliite after the concussion is given. 
The eyed eggs are then measiTred or weighed (we use apothecary scales, weigh 1 
ounce and count them, or count the eggs for one tray and weigh them) and placed on 
the trays, the required number to each tray, and in a single layer in the middle of the 
tray, leaving all the empty si^ace on the outsides next to the frame. They are then 
placed on the foundation board, one at a time; the eggs are covered with a iiiece of 
mosquito netting, which should be at least 2 inches larger each way than the egg 
trays; then the tray is filled with wet moss, tlie part immediately over the eggs in a 
loose manner, and the empty space around the eggs packed tight. This will heli) 
support the next tray above and also prevent the eggs from coming in contact with 
the wood and becoming dry and shriveled. After the trays are all packed and 
placed one upon the other, the hopj)er is placed on top, and the whole cleated 
together, as shown at D (plate 02). The crate is now ready to be placed in the box or 
outside case (E, plate 92). Put dry sphagnum moss, or the material to be used in pack- 
ing, in the bottom of the box to the depth of 3 inches, then set in the crate of 
eggs, idacing it as near in the center of the box as possible, pack the sides well to 
hold the crate in the proper position, and when the top of the hopper is reached with 
the packing, fill the hopper well with ice, then finish filling up the box with moss. 
Never use wet moss, or wet imcking of any kind, for the cushion around the egg 
crate; it will not preserve as even a temperature and it will be liable to freeze solid if 
exposed to a low temperature in transit. After the box has been packed and closed, if 
it should be cut through the center, it would iiresent an ax»pearance like fig. 4, p. 251. 
Amount of mater necessary for incnhation of eggs and rearing of the fishes. — The 
amount of water necessary in any case will depend upon the temperature of the wafer 
and the manner in which it is applied. The water shoxild receive as much aeration 
as possible before entering the compartments containing the fish or eggs. At the 
Wytheville Station, Avhere we have an even temperature of 53 degrees in the hatchery, 
we use in the troughs containing fish and eggs about the following quantities: 
100,000 eggs duriug iucubation, 12| gallons j^er minute. 
100,000 flsh hatching to time of feeding, 30 gallons per minute. 
100,000 fish from 1 to 4 mouths old, 50 gallons per minute. 
100,000 fish from 4 to 6 months old, 100 gallons per minute. 
100,000 fish from 6 to 12 months old, 200 gallons per minute. 
These amounts are amiile; less would do; probably half would suffice if it were 
necessary to economize in the use of water. In reariug-j)ouds more water is required, 
as the circulation is not so good and the outdoor exposure will cause the temperature to 
rise. If water is plentiful I would double the amounts stated above for pond-culture. 
Diseases of trout fry and remedies to be applied. — The most common diseases of 
trout fry are the infianimation of their gills and a slimy and itching skin disease, 
both of which I believe are chiefly caused by impure water. The diseases may be 
caused by muddy water or from the foul and milky water produced iii feeding the 
fish, especially if stale liver is used as food. The food itself may also produce it, but 
I think it generally comes from the fouling of the water. As an ounce of prevention 
is worth a pound of cure, the best plan is to ]irevent, if possible, the diseases by 
keeping the water ])ure. By watching the movements of the fish one can generally 
detect the symptoms of the diseases before they reach an alarming stage. If the 
