Chapter XV: 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.

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.

C. C. C.

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.

INDEX

Advantages of rainbow trout, 72-5

Air bubble in yolk sac, 40

Alders round rearing ponds, 32
at water side, importance of, 19

Alevins, 39-41
diseases of, 40-1

Alpine char, 78

American brook trout, 15
rearing of, 75-6
spawning of, 76

Aquatic creatures, serving as food for fish, 10-2, 62-6

Aquatic plants suitable for deep water, 13
suitable for margins, 13

Aquatic vegetation, importance of, 7
development of, 9

Arrangement of rearing boxes, 34

Artificial spawning of salmon, 83-4

_Asellus aquaticus_, 65

Black spotted trout of the Rocky Mountains, 76-8

Blue swelling, 41

Breeding char, difficulties in, 78-80

Breeding. (See Rearing.)

Brown trout, suitable water for, 14

Bullrushes, 13

_Byssus_, 37-8

Caddis-worms, 61-3
in hatching trays, 38-9

Carp, suitable water for, 18

Char, 16, 78-80
Alpine, 78
difficulties in breeding, 78-80
hatching out of, 78-9
introduction of, to the south, 80
kinds of, 78
rearing, 79-80
suitable water for, 16
Windermere, 78

Charring wood, importance of, 33, 50

Chub, suitable water for, 18

Coarse fish, 88-92
ova of, 90-1

Colorado River trout, 77

Columbia River trout, 77

_Conchifera_, 12

_Corixæ_, 10, 49, 63

Covers for rearing ponds, 31

Creatures, aquatic, serving as food for fish, 10-2, 61-6

Crowfoot, water, 13

Cure for fungus, 50

Cut-throat trout, 76-8

_Cyclops quadricornis_, 12, 48, 65-6

_Cypridæ_, 65-6

Dace, 18, 89-90
suitable water for, 18

_Daphnia pulex_, 12, 48, 65

Dead alevins, removal of, 41

Dead ova, removal of, 37

Difference between beetles and _Corixæ_, 11

Diseases of alevins, 40-1
ova, 37-9

_Dytiscus marginalis_, 11, 49, 58-60, 63

Earth in rearing boxes, 46, 93-6
doses of, in rearing pond, 54, 93-6

Effects of soft food on trout, 24

_Ephemeridæ_, 12, 64-5
larvæ of, 64-5
catching larvæ of, 64

Feeding of the fry, 42-9

Feeding yearlings, 67

Food, importance of, in waters, 5, 7

Fresh-water shrimp, 10, 49, 65
snails, 10-2

Friends and enemies of the fish, 58-66

Fry, feeding of, 42-9
separating large from small, 45
turning out of rearing box, 51-2

Fungus, 38-9
cure for, 50

_Gammarus pulex_, 10, 49, 65

Gold-fish, suitable water for, 18

Grannom, introduction of, 12

Grass round rearing ponds, 32

Grayling, possible harm done by, to trout, 16
suitable water for, 17

Great water moss, 13

Hatchery, suitable spot for, 21-6

Hatching out char, 78-9
ova of coarse fish, 91-2

Hatching trays, arrangement of, 34
caddis-worms in, 38-9
construction of, 32
placing ova in, 34-6
removal of, 42-3
shrimps in, 36

Herons, 60-1

_Hydrophilus piceus_, 59-60

Important points in rearing young trout, 56-7

Inlet to rearing ponds, 29-30

King carp, suitable water for, 18

Kingfisher, 49, 53, 60

Lake Tahoe trout, 77

Lakewort, 13

Leaf screen to rearing ponds, 29

Lobelia, water, 13

May fly, introduction of, 12

Moss, great water, 13

Mussels, 12

_Nautonecta glauca_, 10, 64

Natural food, importance of, 24
natural food for fry, 48-9

Netting for rearing ponds, 31

Ova beds, artificial salmon, 85

Ova, care of, 36-9
dead, removal of, 37
hatching of, 39
of coarse fish, 90-1
of sea-trout, 87
placing in hatching trays, 34-6

Perch, 19, 90-1
suitable water for, 19

Pike, 18-9, 90-1

Planting weeds in ponds, 7
in streams, 8

Ponds for yearlings, 70-1

Rainbow trout, 14-5, 72, 75
advantage of, 72-5
freedom from fungus, 73-4
rearing of, 72-5
suitable water for, 14
spawning time of, 21

Rearing, important points in, 56-7

Rearing box, arrangement of, 34
construction of, 31
cover for, 38, 49

Rearing char, difficulties in, 79-80
fry of salmon, 85-7
fry of sea-trout, 85-7
rainbow trout, 72-5

Rearing ponds, alders round, 32;
grass round, 32
construction of, 22, 27-9
covers for, 31
gravel in, 23
importance of allowing water to run through for some weeks, 21
inlet to, 29-30
netting for, 31
pipes to, 22, 27
removal of yearlings from, 70
separating fish in, 54-6
size of, 23-4
use of earth in, 54, 56, 93-6
vegetation round, 33, 55
willows round, 32, 55

Restocking, best time for, 24

Rio Grande trout, 77

Rudd, 17, 88-9, 91
suitable water for, 17

_Salmo irideus_, 14-5, 72-5
_fario_, 15
_mykiss_, 76-8

Salmon and sea-trout, 81-7

Salmon, artificial spawning of, 83-4
artificial ova beds, 85
mortality among ova and young fish, 81
rearing fry, 85-7
scale upon which rearing should be carried out, 83
success in artificial intervention in stock of, 81-2

Salt, as cure for fungus, 50
dose of, for yearlings, 69-70

_Salvelinus fontinalis_, 15.
(See American brook trout.)

_Saprolegnia_, 38-9.
(See Fungus.)

Sea-trout, ova of, 87
rearing fry of, 85-7

Sea-water as cure for fungus, 50

Separating yearlings, 68

Shrimp, fresh-water, 10, 49, 65

Shrimps in hatching trays, 36

Snails, fresh-water, 10-12

Soft food, effects of, on trout, 24

Spawning time of American brook trout, 76

Stocking waters with food, 7

Stonewort, water-, 13

Suitable fish and suitable water, 14

Trout, collecting wild ova of, 20
ova, management of, 20, 34-9

Turning fry out of rearing box, 51-2
out yearlings, 68-9

Varnishing wood, importance of, 33, 50

Vegetation, aquatic, importance of, 7
aquatic, development of, 9
importance of, at water side, 19
on banks of water, 9, 19
round rearing ponds, 32, 55

Water-boatman, 10, 64
beetles, 11, 58-60, 63
bugs, 63-4
celery, 13
cress, 13
crowfoot, 13
flea, 12, 48
lilies, 13
lobelia, 13
louse, 65
scorpion, 64
starwort, 13

Weeds, importance of, in waters, 7
planting in ponds, 7
in streams, 8

Willow round rearing ponds, 32, 55
at water side, 19

Windermere char, 78

Yearling trout, 56

Yearlings, feeding of, 67
removal of, from rearing pond, 70
separating, 68
turning out, 68-9

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End of Project Gutenberg's Amateur Fish Culture, by Charles Edward Walker