HINTS ON AQUARIUMS
It is better to have several aquariums than one. Often the mistake is
made of gathering together all kinds of savage and voracious creatures
that prey upon each other. Pretty as they are, there is no need to buy
the glass aquariums, and indeed better in every way for the inhabitants
is a large tub put out of doors in a place where there is not too much
sun. Clean sand or gravel should be strewed upon the bottom and in this
water-plants may be fixed. If you have any bivalves they will love to
burrow in it, and some kinds of fish love to rest upon a bottom of this
kind. Large stones should be built to reach half-way up the tub, with
spaces between so that the fish may dart out of the light whenever they
wish. If you keep fish that need running water it will be necessary to
put the tub under a tap, and to pierce a hole near the top of the tub
for the superfluous water to flow away. In this case it will be as well
to cover the tub with a net, or the fish may be found to have leapt
over the edge. Boys may make their own net from the instructions given
in Chapter XIX., or may buy cheap gauze or other similar material.
If the tub is for newts and such things as do not live wholly in the
water, then the stones should be built until they come above the water
and so form a little island. For these creatures the water should not
be so deep, and there should be an abundance of weeds.
Freshwater shrimps and crayfish should have a shallow tub or trough,
a sandy bottom, and places in which they can hide. Here, too, there
must be water running in and out always. By these means we imitate the
natural surroundings of the shrimps and crayfish, for they delight
in the running water of shallow streams that have a bottom of sand
and stones. The outlet for the waste water should be protected with a
grating and probably with gauze, or some of the inhabitants of the tub
will escape.
There are many objections to glass vessels, though some of their faults
may be corrected. They trouble the fish with too much light, but if a
brown paper case of the same size and shape as the aquarium be made it
can be slipped over the vessel and removed occasionally when you wish
to observe the movements of the fish. Glass soon becomes foul, and
needs frequent cleaning. In any case the aquarium should be kept out
of the sun, and for this reason a northern window is best. Whatever
form of aquarium is selected there must be soil and sand at the bottom,
weeds, and shelter for the fish. The bell glass is the least favourable
form of aquarium, but even that may be made tolerable if the hints we
have given are adopted. In the square or oblong form only one side need
be glass and the remaining three sides wood, metal or slate. The sand
that forms the bottom of an aquarium should be quite clean. If you have
found it in the bottom of a swift stream it will not need much washing,
but if from any other place it should be washed thoroughly. Put a large
bucket under a tap, and as the water runs into the bucket strew the
sand gradually into the moving water with one hand, and stir the water
as hard as you can with the other. Keep this going until the water that
runs out of the bucket is quite clean. Even now, however, the sand may
not be thoroughly cleansed. Put a drop of the water upon a piece of
clean glass, and when the water has been evaporated there should be no
sediment. When the sand, plants, pebbles and stones have been arranged
in an aquarium it is best to introduce the water gently by means of a
syphon, a method explained in Chapter XIX. The aquarium may be emptied
in the same way.
There are a number of ways of supplying the fish with the amount of
oxygen they need. One is to change the water frequently, another
already mentioned is to have running water and a pipe for the surplus
water; a third means is to have a fountain, an attractive element
described in Chapter XIX.
These methods, however, are mechanical and artificial. The natural
way of providing the oxygen is to secure the aid of water plants.
These absorb carbonic acid gas, and, having made use of the carbon in
their growth, set free the oxygen, which is waste as far as they are
concerned. Thus in a well-balanced aquarium the fish provide the plants
with carbonic acid gas, and receive back the oxygen which they need;
the plants provide the fish with oxygen which they do not want, but
which is the very life of the fish, and receive back the carbon without
which they would die. Water-beetles, newts and some other creatures
come to the surface for their air, and take no oxygen, or very little,
from the water.
For many reasons the best aquarium is a pond in the garden, for here we
may have greater variety of animal and vegetable life, and beautiful
surroundings of plant life too. The pond should be about three feet
deep, and the banks should slope, so that there will be a little spade
work at first. The bottom may be of clay, but it is better for many
reasons to have cement. The points mentioned with regard to the indoor
aquarium apply here also, but many of the arrangements are more easily
carried out in the pond than in the tank.
$Plants for the Aquarium.$--The duckweeds float and need no planting.
They spread rapidly. There are four kinds: the Lesser Duckweed (_Lemna
minor_); the Ivy-leaved Duckweed (_Lemna trisulca_). Then there is
the American Pondweed (_Anacharis alsinastrum_), a weed that almost
blocks slow moving rivers and canals. It will grow either attached to
the bottom or floating. Not only does it supply the fish with air but
with food also. The Hornwort (_Ceratophyllum demersum_) needs no soil,
and gives off much oxygen, though probably not so much as _Vallisneria
spiralis_, a great favourite in the aquarium. Easier to obtain is the
Water Crowfoot (_Ranunculus aquatilis_), and we may mention also the
Broad-leaved Pondweed (_Potamogeton natans_), Close-leaved Pondweed
(_Potamogeton densus_), the Perfoliate Pondweed (_P. perfoliatus_), the
Curled Pondweed (_P. crispus_), the Starwort (_Callitriche verna_),
the Grassy Pondweed (_Potamogeton gramineus_), and the enterprising
boy will find many others for himself in ponds, streams, and canals.
Foreign plants are sold by dealers. For the garden pond the beautiful
water lilies may be obtained. The weeds should be prevented from
occupying too much space, and if the creatures in the aquarium do not
keep them in check by eating them it will be necessary to remove some
of the plants occasionally.
$Sanitation.$--If a fish dies remove it at once, or its dead body will
pollute the water. To clean a glass aquarium let the water run away
through a siphon until only a few inches remain, then clean the sides
with a piece of rag tied upon a stick. Now siphon the remaining water
away, at the same time supplying fresh water. Do not throw a lot of
food to the fishes. What they do not eat decays and poisons the water.
If there are molluscs in the aquarium this danger is lessened, for many
of them act as scavengers, and they are assisted by freshwater shrimps,
tadpoles, and beetles. The shrimps, however, may eat the living as well
as the dead, and the tadpoles, instead of being allowed to eat, may
themselves be eaten.
$The Food Supply.$--Fish eat the buds and tender shoots of pond weeds.
They may have also a moderate supply of small worms, gentles, different
kinds of larvæ, and what are called ants' eggs. Frogs and toads eat
insects, little beetles, worms, grubs, caterpillars, and newts need an
occasional worm.
$The Fish.$--Many of the fish that swarm in most ponds and streams are
suitable for the aquarium. The carp is related to the goldfish, which
is the golden carp. It is quiet and harmless, and will not interfere
with other creatures in the aquarium. Minnows are pretty, and should
have running water, and the roach is another suitable fish for life
in captivity. The gudgeon, loach, and bullhead serve for bottom fish.
Jack and sticklebacks are extremely interesting, but need a place for
themselves, as they eat any other inhabitants of the same aquarium.
$Fishes as Pets.$--Perhaps, writes one of our contributors, the
most interesting of freshwater fishes to watch is the stickleback,
especially if a pair can be kept during the breeding season in a
good-sized aquarium, so that they have the opportunity to collect
materials and build their curious nest in the natural way.
The male fish develops during this season a most beautiful
vermilion-coloured breast, and is exceedingly pugnacious, so that it is
useless to attempt to keep two males in the same aquarium.
In fact, the stickleback is often so quarrelsome that it is not
desirable to try to keep other fish with him, unless they are much
larger than he is.
The easiest fish to keep alive are the carp (to which tribe the
goldfish belongs) and the minnow.
These can be kept for years without much difficulty, and will not be
likely to injure one another, or any other fish that may be placed in
the same tank.
Small rudd are also very good pets, and are nearly as hardy and equally
harmless.
Roach are easily obtained, and will not quarrel, but they are not quite
so strong.
Perch, on the contrary, will live a long time if regularly fed, but it
will not do to put any smaller fish, except sticklebacks, with them;
yet they look so handsome that an aquarium containing two or three
perch and a pair of sticklebacks is perhaps better worth looking at
than one which can only boast of shoals of roach or other soft-mouthed
fishes.
Dace and chub are pretty and harmless, but require more changes of
water than is usually convenient, or they will soon die.
Tench are tenacious of life, but sluggish and fond of lying at the
bottom. Small bream are fairly lively, and I have found them moderately
hardy. They do not require water of special purity. Gudgeons live
very well, and may be kept with minnows, being good friends together.
The loach and the bullhead are fairly hardy, but have little other
attraction. The grayling is very delicate, and it is not possible to
keep her long, except under very favourable conditions. The ruffe or
pope is hardy, like its relative the perch, and might, if obtainable
(it is not a common fish), be placed in a perch tank, as a humble
companion.
The bleak is almost as delicate as the grayling; and the jack is too
ravenous for any fish to live in his company except another jack _of
his own size_. This about ends the list, excepting that I've left till
the last the noblest of fish--trout and salmon.
With regard to the latter I don't want to encourage a boy in the notion
that he can keep a ten-pound salmon in a tank.
Nevertheless, I have for many successive seasons kept salmon for weeks
or months in a small tank; but these were young ones, very young, about
the size of tadpoles, in fact, and not unlike them in some respects.
They are almost indistinguishable from the young trout with which I
keep them. Of course, they are but babies, and they have their feeding
bottles attached, and do not want feeding till these are absorbed.
To return to trout. These fish, when about a year old, are very
interesting, and if a constant change of water can be secured may be
kept alive for years. Even without this advantage, I have kept them
many months, and have found their little ways very curious.
The trait I objected to the most was the habit of cannibalism which the
larger fish developed. I found one fish of about one and a half ounces
with another about half that size half way down its throat.
This makes it desirable to keep only such trout as are about the same
size together. They will gradually, though very slowly, get tame, and
will come out from their shelter under a weed to eat a caddis as you
drop it from your hand. This was only the case with some of the fish,
others remaining as shy as ever in spite of petting.
It is best to choose fish that have been taken by net, but trout taken
by a fly, or roach taken by a small hook in the lip, will live very
well.
I have kept trout for months that I had caught with fly and carried
home for miles. Some of these were from a quarter to half-a-pound in
weight; but I found smaller fish would thrive better.
For food, caddis or other water insects are best; but gentles would
perhaps do, if the former are not to be had. I found the freshwater
shrimp capital food, as it keeps alive, of course, till the trout is
inclined to eat. One of the chief causes of mortality in the aquarium
is the fouling of water by the decomposition of surplus food. If you
are obliged to use dead matter, such as chopped liver, or meat, be
careful to remove any that may be left.
Flies may be put on the surface, and will be appreciated; but the trout
will seldom take them while you are watching, though they will often
eat the caddis as you put them in, and even chase the shrimps.
On the whole, I think perch are the best fish to make pets of, as they
can be taught even to take worms from your hand, and require much less
water running in and out than do the trout. I've known a perch to live
for years in a tin bath in my stable; whereas the trout would not be
happy without a long tank, and continual change of water.
If you have only a very small aquarium it may be better to be contented
with a few minnows. These, with the water weeds and little fresh-water
snails, which should be in every aquarium, will be quite enough to make
it look pretty.