Bottom Of Ponds

It matters very little of what material the bottom is composed. Anything - mud, clay or moss is good, except gravel, and this is bad, not from the nature of the substance, but because the fish will spawn on it and the eggs be lost. Sometimes a person will wish to construct a pond in a place where there are springs, or to dam up the water and make a pond in a springy place. Under such circumstances it is a good plan to fill the bottom entirely with gravel, as the fish would spawn there in any case. For such a pond make the borders very shallow, so that the little fish may run up into the shallow water and escape from the large fish; or have the pond so arranged that after the fish have spawned they may be removed. Thus the eggs will hatch out and the little ones grow without danger. When the next season of spawning comes the little fish may be removed into another pond and the old ones let in again to spawn. Such a pond is good for any one wishing his establishment to run itself, as with a little care he can raise many fish in it without much trouble. But the gravel must not be smaller than a hickory nut, and from that to the size of a butternut.

Very often the bottom of a pond is porous and absorbs the water as fast as it runs in, so that there is hardly any running from the proper outlet. If you are short of water and wish to use all you can get tor another pond, it is best to cement the bottom. If you have no further use for the water, it makes no difference how it goes off, that is if there are no holes in the bottom large enough to let the fish escape, and the water keeps up to its proper level. Weeds or mosses of any sort are not necessary at the bottom, and if the supply of water is not large they will speedily become a nuisance. The quantity of Trout food which they produce is of no account in an artificial pond where large numbers of Trout are kept, and they tend to foul the water by hiding dead fish and bits of meat. It is best, it possible, to have ponds so arranged that they can be entirely drained. This is necessary, sometimes, tor cleaning or repairing them, and changing the fish from one pond to another. If the slope of the ground is sufficient to permit of such an arrangement, it will often save much labor in pumping or bailing. The drain pipe may be of pump logs, tile or pipe of any kind, and should be fixed in the lowest part of the bottom, or as near it as the level of the ground will allow. Still better would be a regular flume reaching from the bottom of the pond to the top. A bulkhead may be put in to raise the water as high as may be required, and a wire screen the whole size of the flume set a short distance in front of the bulkhead. This large screen has an additional advantage, as the larger the screen the less liable it is to clog up with leaves and moss, and the greater will be the volume of water passing through it.

Screens

Screens may be made of common wire painted with tar - as will be described hereafter - of copper wire, or of galvanized iron wire. The last is the best, as it will last longest in proportion to its cost. The screens for keeping the small fry should be of fourteen threads to the inch, and for one year old fish five or six threads to the inch. Incline the screens at an angle of forty-five degrees, the top being farthest down stream. By inclining the screens in this manner a greater surface is exposed to the water than if they were placed perpendicularly. The sockets should be so made that the screens will fit tightly and yet be easily taken out to clean.

A very good screen for two and three year olds can be made from strips of lath planed and nailed to a strong frame, with quarter-inch openings between them. Or, what is better, the slats should be at least four inches wide so that if a leaf strikes against them it will catch without obstructing the flow of water and lie flat against a single slat, or if it reaches over the edge it will be carried through by the current striking upon one end. It cannot lap around the slat as it would if it were smaller. As for the width of the slats from one another the point to be guarded against is the fish running their heads through far enough to strike their eyes which will produce blindness. The distance they are to be apart will depend consequently, mainly on the size of the heads of the fish, and as fish grow at different rates of speed it will not do to go merely by their age, but for fair sized fish an opening of about five-eights of an inch will answer. This refers to the upper screen, the lower screen, that at the foot of the pond, may be larger as the fish are more cautious about descending where they cannot see their way, just as a man will climb a hill in the dark at his best speed, but will go down very cautiously.

Water Supply

It is immaterial what kind of water is used, whether hard or soft. Neither will so called "mineral water" hurt the trout unless the water is very stongly impregnated. Trout have been known to live and thrive in a stream one-sixth of whose volume was supplied by a strong sulphur spring. The essentials are that the stream shall be reasonably pure, the volume of water nearly uniform or so arranged that the supply taken from it is uniform and the temperature between thirty-six and sixty-five degrees.

One peculiar fact has been noticed in reference to the eggs which is important to those persons who collect eggs to impregnate and sell. The shells of those taken from trout living in limestone waters are found to be thicker and harder than those obtained from soft waters. This may come from the lime in the water, and is an advantage in rendering the eggs more easy to transport with safety, than where the shells are very delicate.

The supply of water necessary for a given number of trout is yet unsettled. For a series of ponds turning out one thousand large fish yearly, the water supply should fill a four inch pipe. This question will be treated more at length hereafter, but it is always safe to have as much water as possible, for within reasonable limits one can hardly have too much - that is to say, if the dams and sluices are solid, and the screens do not clog. It must not be forgotten that abundance of pure water is as essential to fish as abundance of pure air to man.

In saying that ponds must not have a gravelly bottom, we do not mean there should be no gravel. The trout must have access either to the raceway or some other spot of gravel to rub off parasites. This they cannot do if the bottom is wholly of mud and they are excluded from the raceway.