Before I come to the business of fish, I will finish what I had to say about ponds, and the conduct of them; and of that only remains to speak of the course of laying them dry.
As for the smaller waters, I have touched what concerns them already; as for the greater, or principal ponds, proceed thus:
In October, or after, draw the sluice of the first made pond, and lay it as dry as possible you can. It may be the sluice, especially if the pond be many acres, will not vent the water suddenly. That is of no great import, because, as the waters fall, you will have opportunity of fishing with nets, and so clear the fish by degrees; which left to the last, will be too great a burden to clear, and will not be done without damage; besides, the hurry will disorder every thing. If the sluice will not vent all the water from the pan, a labourer or two will soon throw it out with scuppets. Here you find the use of the channels of diversion, spoke of before; for they will keep off all land-waters, if the time should prove rainy, and so permit the pond to empty, and continue dry, which you could not answer for a day without them; and therefore they should be made on both sides of the waters, on each hill one, which will defend the shot of these hills, that otherwise would retard the work.
When your pond is dry, and thus secured, keep it so all summer, and you may make a profit of the soil sufficiently, either by ploughing or feeding. And at Michaelmas next, or a little sooner, let fall the sluice, and turn in all the water you can, that the pond may fill, and at the being near full, it is ready to receive the stock again.
At the same time lay another dry, proceeding as before; which you may do alternately during your whole life: nay, if you have but two great ponds, this is the best course, and will turn most to the profit and feed of the fish, as I shall shew when I speak of feeding.
If your stock be very great, you may let your ponds stand full two or three years, but not longer, unless you delight to see starved lean fish; for such they will certainly be, unless you keep an under-stock by three-fourths continuing in the same water four or five years. And it is a certain rule, that the oftener waters are laid dry, the better the feed of the fish shall be, and more shall be maintained. And a little experience will demonstrate the advantage to be great, as to the size, fatness, and sweetness of the fish.
When your pond is dry, concern not yourself to carry out the mud for the first fourteen or fifteen years; and then let it be only out of the pan whence you took the earth to raise the bank, but never break the turf of the rest of the ground flowed: but when it comes to be a yard thick in mere mud, it is good to take it out; for though mud be good to improve ground, yet, when it is taken from the pond, down to the dead earth, your ground and soil are depauperated, and the water by consequence, which cheats the fish, that is, yourself.
Of the Breeding of Fish.
Having done with ponds, the manner of making, preserving, and using them, I intend next to discourse of fish, and how best to dispose them to maintain the waters in full stock: but before I come to the stocking of waters, I must speak of the course of breeding fish, whereby the stock is to be recruited and supplied.