TREATMENT OF FRY. The successful rearing of fry to later stages was for a long time a prob lem difficult of solution. This has now, however, been perfected with certain species, like the salmon and trout, to a very high degree. The kind and quantity of water and food and the pre vention of diseases are the main points to con sider. A large quantity of water at a low tem perature is one of the essentials to rapid and healthy growth of most species, particularly the salmon and trouts. Limited numbers are put in long rearing troughs—usually the same in which they were hatched—and a large volume of water is introduced in one end. The fry when first hatched have a large yolk-bag which supplies them with food for four or five weeks. About a week before the entire yolk is absorbed they are moved from the trays into rearing troughs. The time to begin feeding them must be ascer tained by trial. If hungry they will rise to a minute particle of food thrown on the surface of the water. At first it is essential to feed them at frequent intervals, and the quantity at a given time must be carefully gauged to prevent them from gorging themselves and to prevent any excess of food from decaying in the water. Liver chopped to very fine particles is the food com monly used. Later the amount of care necessary grows less, so that one meal per day suffices. Larva of flies and various crustacea are then fed to them, and when the fish reaches a consider able size coarsely ehopped-up beef and fish con stitute the main food.
Eggs are not equally hardy at all stages of development. At the time when the eyes begin to show their pigment, or the eggs are 'eyed,' they are usually transported. This is done in trays, the eggs being properly covered and surrounded by sphagnum moss and kept at. a low temperature. This permits the eggs to be transported for thousands of miles without any serious losses. Temporary hatching troughs are built in places out of the way, yet favorable for collecting eggs. The eggs are carried to the 'eyed' stage, and can then be safely transported to more commodious quarters for further development. The United States Fish Commission owns four cars espe cially equipped and exclusively used for the transportation of eggs and young fishes. They are supplied with tanks and cans and suitable means for aerating the water and controlling the temperature.
BIBLIOGRAPHY. United States Fish CommisBibliography. United States Fish Commis- sion annual Reports (Washington, 1371 et seq.) ; United States Fish Commission Bulletins (Wash ington, 1882 et seq.) : Atkin, Chamberlain, and others, "Manual of Fish Culture," in annual Report of the United States Fish Commission for 1897 (Washington. 1898) ; Day. Fish Culture (London, 1883) ; Maitland. On the Ca-Iturc of Salmonidtt and the Acclimatization of Fish (London, 1883) • Gobin, La pisciculture en coax deuces (Paris, 1889) ; Gobin, La pisciculture en catty sale'es (Paris, 1891) ; Max von dem Borne, Fischzucht (Berlin, 188]).