Some use to put up fish in baskets or hampers for carriage, stowing them with grass between; but this is not so good as water, for the grass cleaving to the slime of the fish, rubs and cleans it from the scales; which done, a carp scarce ever thrives after. And although perhaps the fish may live, they will not grow or thrive, because their natural slime, scarce recoverable, is rubbed off; and for the same reason, it is not good to let carps lie at all in grass, but keep them always in water, to preserve them from bruises, and losing their slime.
Of Nurseries to Ponds and Fish.
Generally speaking, the fresher air and cleaner soil your water hath, the better fish thrive. Wood of any sort near the water is bad, not only from its hindering the wind and sun from purifying the water, but from the leaves falling in, and rotten wood; both which are pernicious to fish. But osiers and willows may be allowed of, without much inconvenience. Oak boards, or timber laid in water, as sometimes is done to season, will in all probability destroy all your fish; and likewise hemp laid to rot; all which are therefore to be avoided. Dung-hills, stables, or cow-houses, permitted to drain into ponds, are very ill neighbours, and most especially wash-houses, which certainly spoil a standing water.
Of Frosts, and the Ways to save the Fish in them.
The great plague and bane of fish in moats, great and small, and other little standing waters, are great and sharp frosts. I have used all the tricks that I have heard of, which are not a few, or could devise, to save my fish in such waters; and yet in ten years time I have lost three or four thousand carps. But yet I have found ways to save the life of many a fair carp, when my neighbours have lost all; which I shall declare as my own experience, and may be profitable upon like occasions to any that will use them.
First, as to the sorts of fish that suffer most, I can only say, that the tench, if any, is frost-proof, and will shift in extremity; but if the frost be intense and long, the other sorts, as carps, eels, pike, perch, and roach, will go near to perish; and I have found not any great difference of hardness, but when one fish complains, they are all in imminent danger.
The waters most obnoxious to frosts are such as are standing, shallow, or small. For if there be either a water-current, or a fresh spring, no fish dies for frost. If an hard winter succeeds a very dry summer, the fish suffers most. If the ponds are large and deep, such as I have directed to be made upon the channel of water, which may not run but upon floods or rain, the fish will never die in frost there; but such waters you must look upon as the asylum for the securing the fish in extremity; and all that you can put in there alive, though through a hole in the ice, will certainly live. If the bank of a pond sews, it will preserve the fish in frost; the reason, as I imagine, is, because where the water sews out, the air will bubble in, which relieves the fish; or perhaps it might put the water into some degree of motion. If so, the stirring water with a board flat upon a pole put under the ice, might do good; but this is conjecture.
The symptom of mortality to your fish in time of frost, is, their shewing themselves; which if you perceive in the least, conclude all are going; and without a thaw, that water will not keep them alive. For it is the nature of fish in cold weather to lie as close and deep as they can; so that nothing but the pangs of death shall make them move. If no holes are broke, they will rise and stick to the ice, and be frozen to it; if there be holes, they will move about them, as if they came up for fresh air.