The way in which dace will increase when put into a suitable water is, if possible, even more remarkable than what happens in the case of the rudd. I will quote one instance, which proves this very conclusively. A few years ago there were no dace in the Sussex Ouse. Pike fishermen, however, used to bring live dace to use as baits. Some of these escaped, or were set free by the fishermen at the end of their day's fishing, and now the Sussex Ouse contains more dace for its size than any other river I have ever seen.
While rudd thrive best in a pond or lake into which a stream flows, dace require a river or stream to do well. They will, however, thrive and increase rapidly in a river where trout are not a success. A muddy bottom with occasional quickly running shallows, seem to constitute the best kind of water for dace. The largest, and by far the best conditioned dace I have seen, have come from the tidal parts of rivers, where the water is brackish at high water. Dace from such a water have also the advantage of being very good eating, as they have, as a rule, not got the unpleasant muddy taste usual in this fish.
Perch and pike will thrive both in rivers and in ponds or lakes which have a supply of water from a stream or from springs. They both increase in numbers very rapidly, and when protected, are more likely to require thinning down every few years, than artificial assistance from the amateur.
The king-carp is the best fish for the amateur who wishes to obtain good bottom fishing from an absolutely stagnant pond. This fish is much bolder and a more free feeder than the common carp. It increases so rapidly in numbers, and is a hard fighting and lively fish.
Most of the coarse fish deposit a much larger number of eggs than do any of the Salmonidæ—that is to say, in proportion to their size. In stocking a water which contains no fish, the amateur may wish to hurry on the process of nature in the case of coarse fish; and, fortunately, this is fairly easily managed. In the case of perch, rudd, pike, and carp, but little change of water is required to hatch out the eggs. The eggs of these fish take but a short time to hatch; and if they are protected, and this protection is also given to the little fish for a few weeks, it will generally be found that an amply sufficient result is obtained. The eggs should be spread out carefully on wicker-work or the lids of baskets and kept in the light. A trickle of water which is sufficient to change the body of water in the pond in which the ova are put will, as a rule, be enough. The amateur must be careful that the pond in which he hatches the eggs does not contain any of the many enemies I have described in former chapters. If it is at all possible to protect the eggs and the little fish, it is best to hatch out the eggs in the pond which it is intended to stock, for it is exceedingly difficult to keep the newly-hatched fish in a rearing-pond on account of their very small size. It will be necessary to use muslin or flannel screens instead of perforated zinc. Care must be taken that there is not too great a flow of water, as this will cause the little fish to be drowned at the outlet screen.
APPENDIX
THE USE OF EARTH IN REARING PONDS
[From a correspondence upon the subject which appeared in Land and Water]
Sir,—In your last issue I have read with pleasure the eminently practical notes on fish culture by Mr. Charles Walker. He is perfectly right in all he says with reference to the useful and preventive results of the use of "common garden" earth, or vegetable mould in checking any fungoid development, Saprolegnia or other. It must, however, be admitted that the said addition is not an element of beauty in a box; therefore it should be avoided, or only used when necessity dictates. However, the fry, when thoroughly restored to health, may be transferred by muslin net to another box free from earth should it be necessary to count out certain numbers for the satisfaction of customers' orders. Again, the earth employed may, and in some waters does, give rise to other ill effects on the health of the "fry" or young fishes. Affection of the eye is not unheard of as the result of over-use of earth. Perhaps the best way to obviate any trouble of this nature would be to pound and dry the earth, and keep it in a canister or other closed vessel till required for use. Spores of fungi are nearly, if not quite, omnipresent; and their effects are so insidious that too many precautions cannot well be taken to avert the introduction of "trouble" in the hatchery. Indeed, were it not for the risks arising from attacks of fungi, pisciculture, as now understood and carried on, would be an unalloyed pleasure and unbounded success. We can practically hatch 995 out of 1,000 eggs, or thereabouts. It is the risks of rearing that stand in our road, and these, as time goes on, and experience increases, must diminish. There would appear, then, to be a good time coming for fish culture, and those who earnestly follow it.
Practice is the only safe guide, as circumstances, geological, physical, and meteorological so vary the conditions of works that no definite rule of procedure will avail. Earnest work and close observation, combined with ready resource, are the only safe guides to success. Troubles of some sort are sure to supervene; the man who succeeds is he who can anticipate, and so remedy them. To be always on the watch and notice the first indication is a very safe maxim, more easy to inculcate than to put in practice.