Growth

There will be a great difference in the growth of the fish noticeable after the first few weeks of their existence. Some, of course, will be larger and more vigorous than others from their birth ; but of those apparently of the same size and health when one month old, some at six months will be four times the size of others; this, too, when grown in the same pond and under the same circumstances. They will begin to eat each other when very young. A Trout only a few weeks old begins to show symptoms of fight, and will kill his weaker brethren when they get in his way by biting a piece out of their tails. In two or three months, when some of them get to be double the size of others, they will swallow the smaller ones. We have taken a Trout one inch long out of another only two inches long. It would seem to be advantageous, therefore, to sort them out every little while, and put the same size by themselves ; but in practice this is very difficult, and the less a trout of any size is handled, the better; besides, if they are fed well they lose their disposition to eat each other. Therefore, the trout of each year may be left by themselves with very little probability of losing more by cannibalism than would be killed in sorting out and removing.

Salmon and salmon-trout do not require so much care as trout. Salmon, both the eastern and western, prefer to remain in the strong current of the stream, and not in the quiet eddies or dead water like trout. In this way they receive the element in a purer and better aerated condition. They grow more rapidly, and are sooner out of danger of infantile diseases. A curious fact has been observed in reference to California salmon, and probably the same rule applies to all fish. They will grow much more rapidly in warmer water than in the cold spring water in which they were hatched. Nor does the change produce any diminution of health. Fry taken from the hatching troughs and placed in tanks with the water at sixty degrees, became, in the course of five months, five times as large as those that remained in the water of a temperature of about thirty-five degrees. They were exceedingly active, very few of them died; they ate voraciously, and their colors were very remarkably brilliant.

California mountain trout are also more vigorous in every way than the eastern trout; they are not so handsome, having no carmine specks, and much duller colors on their sides and bellies, but they are hardy, lived well in confinement, and grow rapidly. They take a fly readily and furnish excellent sport to the fisherman, while their flesh which like that of our trout is sometimes white and sometimes red is not to be surpassed as food. So strong are they that they are difficult to manipulate in extracting the spawn from them. They are hard to hold and will only give down their milt or spawn when they are ready. The person handling them must wait for his opportunity. The only California trout which were ever acclimatized in the eartern states up to this time (1878,) were hatched and grown in the New York establishment. They commenced spawning March 14, 1878, three years after they were imported in the egg. They yielded more eggs than the eastern trout in proportion to their size, and the eggs were slightly larger. They continued spawning until May 25th, and began to hatch in forty-five days. By the report of the Utah Commissioner of 1878, it is said that the western trout spawn in May, but as no spawners were taken by the Commissioner and no eggs obtained by him, he may have been too late, and the fish which he obtained instead of being all males, as he supposed, may have been spent fish.

Precaution Against Escape

There will always be a difficulty in so arranging ponds, screens, outlets and inlets as to keep the young try in their proper pond. The water is very apt to work holes around the screens, or rather around the boxes containing the screens. The young fry will make their way through a wonderfully small hole, no matter how long the distance may be. They will also get through between the screen and the socket, unless these are very well fitted together, and wherever there is a crack into which they can get their large heads, they will put them in so tightly that they cannot extricate themselves, but will die. In short, wherever you can run the big blade of a jack-knife, there the young trout will go. In making a pond for them, it is best to beat the edges with a spade until they are perfectly smooth, or, better yet, to put a board around the edges to the depth of a foot.

Cleaning Screens

If the screens are not kept well cleaned, two consequences follow. First, the water runs over the top of the screens instead of through them, and the young trout escape; and second, when the screens are taken out to be cleaned a rush of water follows their removal, carrying away with it numbers of trout into the next pond. Whenever you are going to clean the screens drive all the trout from their vicinity, then take the screens out and wash them with a stiff brush." They may be first raked off with a rake if they are made of slats, and then taken out and cleaned. They will require attention always once and sometimes twice a day.

Diseases

This part of fish raising is least understood as yet. After the egg sac is absorbed and the fry begin to swim about, a sick one is very easily distinguished. The healthy trout swim in the current with their heads up stream, darting about here and there after minute particles of food. The diseased ones wander about listlessly, swiming round and round continually. They may also be known by the size of their heads, which appear much larger than their bodies. The head of a young trout is the largest portion of the fish, even when well, but when sick the fish appears to be all head.

Before the food sac is gone the trout is often afflicted with a swelling over the sac; a membrane forms there, swells out large and is filled with a watery substance. We call the disease the " dropsy," or " blue swelling." Sometimes the trout may be saved by making an incision in the swelling and letting out the water; but as with care only a few of them are affected in this way, it is better for the fish culturist to hatch more eggs than he expects to raise than to bother with a surgery he does not understand. In other words, hatch more than you want, and keep the strongest and best.

There is a small worm which is one of the greatest enemies which the young fry have. It spins a web in the water to catch the young fish, just as a spider does on land to catch flies. The web is as perfect as that of the spider and as much mechanical ingenuity is displayed in its construction. It is made as quickly and in the same way as a spider's, by fastening the thread at different points and going back and forth until the web is finished. The threads are not strong enough to hold the young trout' after the unbilical sac is absorbed, bnt the web will stick to the fins and get wound around the head and gills and soon kills the fish. It is even more destructive to white fish, which are much smaller than trout when first hatched. The threads spun by this worm seem to be much finer than the common spider's web, and they are not visible in the water until the sediment collects upon them. They can then be seen very plainly. The webs can not be spun where there is much current and can be easily seen in still water by a close observer.

But after all the principal causes of the death of trout are, first and foremost, starvation, nine-tenths of all the young that die are literally starved. Secondly, rough handling; the least twisting or wringing of a fish with the hands will kill it. Thirdly, lack of sufficient water, and fourthly, the temperature of the water. These four difficulties, all of which are preventable will account for the death of most of the fish that die.