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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.

There can be no question but that the practical removal of difficulties in the path of fish culture is work of the highest value, well worthy the attention and acknowledgment of those in authority at Whitehall and elsewhere at home, as has been the case abroad.

SIR, Your correspondent “C. C. C.” in Land and Water of last week disagrees with the constant and free use of earth, which I had advocated in my article on fish culture which appeared the preceding week. Naturally one must admit that earth at the bottom of a pond is not so great an element of beauty as is clean gravel, but the advantages are so many, that beauty must give way to usefulness. Besides this, “C. C. C.” must know that it is almost impossible to keep the gravel clean enough to look pretty, when the water is inhabited by a large number of little fish which are being constantly fed. I cannot at all agree with his advice that “earth should be avoided, or only used when necessity dictates.” I believe that one of the first principles of success in fish culture is always to prevent any disease or mishap, rather than to wait for, and then try to remedy it. Trout in their natural surroundings get a dose of earth every time that there is a spate. It is very evident that the earth contains some ingredients which are not only beneficial but almost a necessity to the fish.

I have never heard of earth as an actual cure for “fungus” and should hardly think that it is active enough. There is, however, no doubt that it is one of the best preventatives to “fungus,” for if it is properly and freely used it stops all chance of any decomposing material being exposed to the action of the water, and laying the fish open to the chance of a great many evils.

If suitable earth is used once a week, and even oftener on occasions, it can do no harm, and will keep the fish safe from a great many risks besides doing them very material good. I do not of course mean that the usual weekly dose should be a large one, as this would fill up the pond before the end of the season, but that a small dose should be given generally, and a large dose occasionally. I am quite sure, too, that clean earth with some nice weeds growing in it, looks better than gravel which is dirty. Gravel shows the dirt so much, that it is almost impossible to keep it looking nice where there are many fish, and it also gives the water free access to any decomposing matter.

I have never come across a case of disease caused by the use of earth, and should like to hear the details of “C. C. C.’s” experiences with regard to this matter.

CHARLES WALKER.