TROUT. REARING PONDS, BOXES, AND HATCHING TRAYS

Having decided upon a suitable spot, the amateur must now proceed to make his ponds. Whether he derive his water supply from a spring or from a stream, the amateur had better bring it into his ponds through a pipe. A three-inch pipe will be large enough for a pond thirty feet long, three feet wide, and two feet deep at the deepest part. It is a good thing for the water to fall, some inches at any rate, through the air before it reaches the pond, and in a series of ponds with only one supply, the water should flow through an open trough with stones and other impediments in it, between the ponds. The ponds may be lined entirely with brickwork faced with cement, and in this case the sides should be made perpendicular. The cement should, however, be exposed freely to the action of the running water for a couple of months at least before any ova or fry are introduced.

Another plan, and a simpler and less expensive one, is to face only the ends of the ponds with brick and cement work, carrying the brickwork into the earth on each side, as shown in Fi. In this case the sides of the ponds should be slightly sloped. It is advisable if possible to make the outlet at the level of the bottom of the pond, if the pond is lined with cement, but if the pond is only cemented at the ends, it is better to have one in mid-water or even near the surface. As I have said before however, an outlet should be made at the level lowest part of the bottom, so as to facilitate the emptying of the pond. The pond should however be made shallower at the lower end.Section of the upper end, and of the lower end of such a pond.

The open trough between ponds in a series should be at least three yards in length, but it is better if not straight. Stones and gravel should be put in these troughs in order to make the water as rough as possible, and if some fresh-water shrimps can be introduced so much the better.

If the water is taken from a stream, a leaf screen must be placed at some distance in front of the inlet. This may be made of a hurdle fastened to strong stakes sunk into the bed of the stream. The opening of the inlet should be at least double the size of the sectional area of the pipe through which the water is carried to the ponds, and should be some distance, a couple of feet if possible, below the surface of the water. It is a good thing to put a wire cage over the inlet, and under this a perforated zinc screen is necessary. The inlet from the stream should be so placed that it is easy to get at and clean. The best form of covering for the inlet into the pond I have seen, is a zinc cylinder, the base of which fits over the end of the inlet pipe. The part of this cylinder, which projects 18 inches beyond the pipe, is perforated, as is also the flat end. This can easily be taken off and cleaned, and breaks up the water, making it fall into the pond like a shower bath, causing considerable aeration.

The inlet from the stream should have a trap with which the water may be shut off, as also should the outlet from the pond. When the cylinder on the inlet into the pond is taken off for a minute or so to be cleaned out, both these traps must be closed. This lessens the chance of any creatures likely to do harm getting in during the cleaning. The perforated zinc screen at the inlet from the stream will probably stop any such creatures, but too great care cannot be exercised, and it is always best to be on the safe side.

Movable covers of netting over the ponds are most certainly advisable, particularly if the rearing ponds are in an unfrequented spot near a stream. On one occasion I caught four kingfishers during a period of three weeks, all of which had in some way got under some herring net, which was pegged out carefully over a rearing pond containing trout fry. I never found out how they got in, but once in they were unable to escape.

Ponds such as I have described are of course for the fry when they have reached a certain size, and have already begun to feed well. Other appliances are necessary for hatching out the ova and for the young fish when first hatched. A very good apparatus may be made from a champagne case. This should have large square holes sawn through each end, leaving enough wood to ensure strength and solidity to the box. The box should then have two coats of asphalt varnish, and the square apertures covered with fine perforated zinc. A still better box may be made at a small cost. This consists of a box with a wooden bottom and perforated zinc sides which are supported by a stout wooden frame.

Beyond these boxes all that are required are some perforated zinc hatching trays. These should be 1-1/2 inches deep. They are very easily made, and the ova hatch out well in them. Though ova sometimes hatch out very successfully even when piled up in two or three layers, it is safer to have them in a single layer. The trays should be suspended in the boxes, and the boxes in the ponds close to the inlets, so that a good current of water may flow through them. The bottom of the boxes should be covered with a thick layer of gravel, but the trays are to be used without gravel. It is advisable to have as much grass as possible round the ponds, and such trees as willows and alders should also be planted round them. Willows and alder sticks planted in the early part of the year come into leaf in the same spring, and afford shade to the young fish in the summer. Some suitable weeds should also be grown in the rearing ponds. Water-cress, water-celery, water-lobelia, starwort, and water-milfoil, are all good. They should be arranged, however, so as to prevent as much as possible the little fish finding hiding places, and it is for this reason also that I have recommended slightly sloping banks when the sides of the ponds are not made of cement. The weeds should be planted some time before the little fish are turned out of the boxes.

Finally, I must caution my readers again on one or two points before I leave the subject of the hatching trays, rearing boxes, and ponds. Enamel, varnish, or charr all woodwork thoroughly, leaving no speck of wood bare and no crack open. Let the water run through and over all your ponds and apparatus for as long as possible before you begin operations.