Diseases And Enemies

The diseases to which adult trout are subject are numerous and often fatal. Some times a trout will be observed to have a white fungus growing upon it in spots. This will spread over the fish until it dies. Sometimes fish will turn to a black color. This always seems to be an indication of blindness, as we have never observed this peculiar color unless the fish was partially or totally blind. The fungus which grows upon the fish is probably not a disease, but is caused by, or is the indication of a disease. Nothing is known about remedies. If only a few trout are affected, take them out as they will be sure to die. If the trout begin to die in numbers, change them to another pond, if possible, or give them more water. This is all we can do fur them. The dead trout should be taken out of the pond as fast as they are discovered. They will rise to the surface only in very rare cases, but generally sink to the bottom, and if there is much moss in the pond they are lost to sight, and decaying on the bottom will foul the pond. If there is much sickness among the trout, we generally consider it a sign of insufficient water.

There are but few enemies of trout in artificial ponds. If the ponds are near the house, and people constantly about them, there will be no trouble with the birds which usually prey upon fish - such as the kingfisher, fish-hawk and crane. Even if the ponds are some distance from the house, the water will probably be too deep for the fish-hawk and kingfisher to do much mischief, as it is only in shallow water that they can be certain of their prey. Cranes will wade into the water and take all that comes within reach of their long bills - whether frogs, snakes or fish. But they are very few in number, and the trout are wary. If any of these birds appear, shoot them. Muskrats sometimes get into the ponds. They can not often catch the trout, but will destroy the young and the spawn if they can get at the troughs, and they eat many of the insects on which the trout feed, besides they makes holes in the banks of the ponds and let the water off. A few traps will soon dispose of them. It may be worth while to mention here the manner of catching them. Find out the places where the muskrats go into the ponds. They will make a little bare path, or run on the edge of the bank, by always going in and out at the same place. Then set a trap (a common game trap, such as is sold in all country stores) in the water, so that the plate of the trap will come in the middle of the run and about a half an inch under water, taking care to place the jaws of the trap in such a direction that when shut they will be in a line with the run. Then stake the chain into deep water. No bait is necessary. If any bait is used a sweet apple or parsnip may be stuck on a stick and the stick stuck into the bank so as to bring the apple just over the jaws of the trap when closed. The muskrat comes through his run, steps on the pan of the trap and springs it. He tries to take it with him to the shore. If he succeeds in doing this, he will likely get out in some way; for instance, if he is caught by the leg, he will sit down and knaw it off, in order to get free. But as the trap is staked out into the water, he can not get to shore, and will be drowned by his struggles and by the weight of the trap, for he can not survive under water very long without rising to the furface for a supply of air.

Water snakes can not do any damage to the large trout, but will certainly eat all the little fish they can get hold of. Even if they do no injury, they are not of any advantage, and may as well be disposed of.

Cray fish very seldom eat the young fish. They will lie on the bottom, hidden in the mud, with the joint of the claw wide open and ready ; then if any unfortunate troutling passes within reach, his doom is sealed. Crayfish do much more mischief by their burrowing propensities. They will make holes out of the pond, or from one pond to another, through which the water escapes, and very often the young fish also. The cray-fish is the scavenger of the water, and it may be a question whether a few of them will not do as much good, by disposing of decaying animal matter, as they do harm, by destroying a few fish ; but they will eat spawn and the fry still encumbered with the sac. The greatest fear of all fish-raisers is that their fish will be stolen at night. A few old logs, stones and branches of trees strewn on the bottom of the pond, will make it impossible to drag the pond with a seine. Catching them by hook and line is the only means ; and if the fish are well fed daily, it will take more time to catch a mess than thieves can usually spare.

Trout also find enemies in their own kind. The only way to stop them from feeding on each other is to give them plenty of other food. It may be as well, perhaps, not to feed them on small fish, unless these are chopped up fine, for the reason that trout soon accustom themselves to certain kinds of food, and will refuse anything strange. If they get into the habit of feeding on small fish, they will not be likely to make a distinction between trout and any other fish. Certain old trout also become unusually destructive to their brethren. Like the "rogue-elephants," and the "man-eaters," among the lions, they become morose and sullen, live apart from the rest, and make war upon everything around. When you find one of this kind, spear him at once, as there is no cure, and he will invariably destroy more than he is worth. It may be worth while to mention here how one trout eats another. An old trout will catch a smaller one, in some cases one-half of its own size, by the middle, and with its strong jaws hold it fast and swim around with it, while the prisoner worries and struggles to get free. This performance lasts until the victim gets loose or is exhausted, being continued sometimes for half a day. If the little fellow gets free, it is usually only to die a lingering death ; for the breaking of the skin is fatal. When it is exhausted, the old rogue, dropping his victim, which until this time he has held by the middle, siezes it again by the head, and slowly swallows it whole; the operation sometimes taking several hours, and while in progress making the fish look as it had no head, but only a tail at each end.

In some localities minks are very destructive. These animals are particularly to be dreaded because they do not only kill what fish they want to eat, but will take" out fifty or one hundred before they stop, and having found a well stocked pond, they will resort to it again and again. The best way to trap them is as follows: Make a box eighteen inches long by six: inches broad and deep, leaving one end open, set a common game trap (such as used for catching muskrats) in the open end of the box in such a position that when the jaws are closed they will be in a line with the length of the trap. If it is set cross-ways it will be apt to throw the mink out instead of catching it. Put the bait in the further end of the box - a piece of meat or a dead fish will answer for bait - set the trap and cover it over with a large leaf. Now, there is only one way for the mink to get at the bait, which is by walking over the trap. Some trout-breeders also try to raise mink for profit as their skins are valuable; but their habits of eating fish and their custom of getting out of almost any box or yard in which they are confined do not make them agreeable neighbors for the trout.