Stocking Waters With Food
It may seem somewhat superfluous to say that fish cannot live in any
water unless that water contains the food supply necessary for them to
thrive upon, and yet this is the point most often overlooked in stocking
waters with fish. Small attempts at stocking with creatures suitable for
food, particularly after the fish have been already introduced, are not
at all likely to succeed. Such an important matter when treated as a
/>
small afterthought is almost sure to end in failure of the whole
business of stocking.
But a small amount of thought will convince any one that in order that
there may be a sufficient amount of animal life in a water, there must
be an adequate vegetable life, for weeds are almost always necessary to
the well-being of the creatures which serve as food for fishes.
In the case of a pond it is generally fairly easy to introduce a good
stock of suitable weeds. The best method is to let the pond down as low
as possible, and then to plant some weeds round the margin; the water is
then allowed to gradually fill up the pond, and as it rises weeds are
planted round the rising margin of the water. In ponds which cannot be
emptied at all, or not sufficiently to carry out this plan, weeds may be
planted in an easy but not quite so effectual a manner. They may be
planted in shallow baskets containing some mud from the bottom of the
pond, and then lowered in suitable places from a boat, or bundles of the
weed may be tied to stones and dropped into the water in a similar
manner.
These latter methods are, of course, not so good as actually planting
the weeds round the advancing margin of the water, for success depends
to a certain extent upon chance. Some of the weeds thus planted are,
however, sure to take root and grow. Plants of different kinds, of
course, are necessary at different depths and on different kinds of
bottoms, and good kinds are necessary at the margin of the water as
well. I give a list of some suitable plants of each kind at the end of
this chapter.
Similar methods are used in planting weeds in rivers and streams to
those used in ponds. If the weeds are planted in baskets, the baskets
must, of course, be weighted when put in a position where the current
can act upon them.
Besides vegetation in the water, vegetation on the bank is of
considerable importance. I shall deal with this at a later period more
fully, as trees and bushes, besides harbouring many insects which serve
as food for fish, have also considerable importance in giving cover to
the fish and to the fisherman who is pursuing them.
I think that in the case of a bare water, a year at least should be
devoted to developing a good supply of vegetation. This will generally
produce a considerable amount of animal life, without any artificial
help, but judicious help will be sure to accelerate matters to a
considerable extent. I would, however, advise the amateur not to attempt
to introduce a quantity of creatures into his water, until the vegetable
life therein is well established. For instance, though fresh-water
snails are desirable in every trout water, if introduced in large
numbers into a water in which the vegetation is small and not well
established, they will eat down the weeds too much and then die off from
disease caused by want of sufficient nourishment.
Having established the vegetable life well in a water, and developed it
to a considerable extent, the amateur may begin to examine his water,
and find out how much animal life exists there, and to stock with
creatures suitable for food, according to what he finds in the water.
Fresh-water snails are always desirable. In streams, or in ponds with
streams running into them, the fresh-water shrimps (_Gammarus pulex_)
should always be tried. It does not do in some waters, but where it does
thrive it increases very rapidly, and forms about the best article of
food that can be given to trout. _Corixae_, which thrive in ponds and
sluggish waters, should always be introduced. They increase rapidly, and
are taken by most fish, particularly by trout. The amateur should be
careful when he introduces these creatures to make sure that he is
putting in the right creature. The water-boatman (_Nautonecta glauca_)
is a member of the same family, but is no use as food for the fish. He
swims on his back, is longer and narrower than are _Corixae_, which do
not swim on their backs, are smaller, broader, and live much more under
water than the water-boatman. It is generally advisable to avoid
water-beetles, as most of them are more likely to do harm than good,
such a number of our water-beetles being carnivorous. They will probably
not harm adult fish, but they will destroy ova and fry. I have known a
_Dytiscus marginalis_ kill a trout of nearly a quarter of a pound in
weight.
In order to make sure of not introducing carnivorous water-beetles into
a water, I think it best as a rule not to introduce beetles at all.
_Corixae_ are, however, so like beetles, that many people call them
beetles, and therefore I will give a few points which will make them
easily distinguishable from each other. In beetles, the wing-cases
(elytra) meet exactly in the middle line, in _Corixae_ and other
water-bugs, the anterior wings, which resemble the elytra of beetles,
overlap, which causes the line on the back to curve away to one side at
the lower end. In beetles the wings which lie under the wing-cases are
folded up on themselves, and when spread out are much larger than the
wing-cases. The wings are transparent and very delicate. In _Corixae_ the
posterior wings, which lie under the hard and horny anterior wings, are
a little shorter than the anterior wings; they are not folded up on
themselves and are not so delicate and transparent as the wings of the
beetle.
Such small creatures as _Daphnia pulex_, _Cyclops quadricornis_ and
_Rotifera_ should be introduced into ponds.
Snails (_Gasteropoda_) may be roughly divided into three classes,
according to the shape of their shells: (1) Flat-shaped coils (type
_Planorbis corneus_); (2) Oblong-shaped, somewhat like a trumpet (type
_Limnaea stagnalis_); and (3) Ear-shaped (type _Limnaea auricularia_).
_Limnaea auricularia_ is particularly suitable for deep waters, and _L.
pereger_, whose shell is of type 2, is a most valuable addition to the
food supply in any fish pond. It is one of the commonest of our
fresh-water snails.
Mussels (_Conchifera_) are another valuable article of food. There are a
great many different kinds, and the larger ones should, as a rule, be
avoided. _Sphaeriidae_ and _Pisidia_ are probably the best.
In many cases it is advisable to attempt the introduction of some flies
which are not present. There are several cases in which the May-fly has
been successfully introduced, and also the Grannom. Small _Ephemeridae_
seem to me preferable to any other flies.
With regard to suitable plants for comparatively deep water in ponds or
lakes, lakewort and stonewort grow on the bottom, and do not, as a rule,
attain any considerable height. White and yellow water-lilies also grow
in fairly deep water; the water-lobelia is also an excellent plant for
ponds.
In streams some of the best plants are water-crowfoot, water-starwort,
and the great water moss. Anacharis should not be introduced into any
water, either pond or stream, unless it can be kept down easily. It will
otherwise become an unmitigated nuisance.
Marginal plants are a very important consideration, and plenty of them
should be grown. Water-celery and water-cress are perhaps the best
food-producing marginal plants that can be grown. Bullrushes and
brooklime are also good, but the bullrushes must be planted
judiciously.