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School Aquariums
Nature Bulletin No. 577 October 24, 1959
Forest Preserve District of Cook County
Daniel Ryan, President
Roberts Mann, Conservation Editor
David H. Thompson, Senior Naturalist
SCHOOL AQUARIUMS
Everybody seems to be born with a special curiosity about animals that
live in water. Partly, this is because the underwater world is so different
from our life on land partly because aquatic animals are of so many
strange kinds or are so secretive that they are "sights unseen" to most
people.
The best way to get better acquainted with many of the smaller ones is
to catch, in a pond or stream, some small fish, tadpoles, crayfish, snails,
or any of a wide variety of water insects. Carry them back home or to
school in a bucket of water. Then they can be put in glass containers
where they can be kept alive, their habits watched, and their life
histories studied.
A wide variety of containers are suitable for aquariums, depending on
the amount of money and space available. They may be rectangular
tanks with glass sides and covers, ranging from two to ten gallons in
capacity, or even larger. They may be wide-mouthed gallon jars, battery
jars, fruit or mayonnaise jars. All containers should be thoroughly
cleaned and rinsed before using. Enough coarse sand or gravel is
needed to cover the bottoms of the tanks and a few of the jars to a depth
of one or two inches. Previously, this should be washed repeatedly in
running water until it is free from sediment and debris. This gives a
natural background and an anchorage for a few water plants. A handful
of pond mud and water-logged leaves in another jar often develops a
wealth of microscopic life.
Clear pond water is best for native aquatic animals. If this is not
possible, use tap water which has been exposed to the air in open
containers for a day or more to allow oxygen to dissolve and chlorine to
evaporate. Aquariums placed in a north window, or in diffuse light,
thrive best. Direct sunlight for more than short periods is likely to
overheat the water and stimulate objectionable growths of algae. Unlike
tropical fish, which must be kept warm, our native water life is
accustomed to winter cold and lives well in school buildings when the
heat is turned down over week ends and holidays.
Beginners
often overcrowd their aquariums. Too many animals are
almost certain to exhaust the small amount of oxygen which can be
dissolved in water, causing all of them to suffocate. A good rule is to
allow no more than one inch of fish to each gallon of water. Thus, a 5-
gallon tank can support only two 2 to 3-inch sunfish, bullheads or
minnows. Plants should be used sparingly because, although they
produce oxygen in light, they also use oxygen in darkness.
Crayfish, unless very small, prey on other aquarium animals and must
be kept in a separate container, preferably in less than an inch of water
with gravel heaped on one side where they can crawl out occasionally.
They are primarily carnivorous and can be fed small earthworms or bits
of hamburger.
Overfeeding is a common mistake. Sunfish and bullheads can be fed
small earthworms, insects or bits of hamburger but they should be given
only as much as they will clean up on the spot. Uneaten food spoils,
fouls the water, and uses up the oxygen, causing animal life to smother.
Pond snails and frog or toad-tadpoles eat plant materials -- bits of
lettuce leaf, algae and sediment. Most of the larger aquatic insects,
especially the adults and young of many kinds of water beetles and
water bugs, are predacious, taking only live food, and must be kept by
themselves. Live food can be caught for them by sweeping a
smallmeshed dipnet through submerged trash and vegetation in ponds.
Of all schoolroom aquarium demonstrations, the most dramatic is the
day-by-day development of frog or toad eggs inside their protective
jelly.
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Update: June 2012
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