6
MAINTAINING FISHES
been utilized by fishes but has been permitted to
stand long enough to develop a population of microscopic and semimicroscopic plants and animals. Sunlight and the addition of a small amount of organic
matter result in more rapid and complete aging. In
addition to involving the development of microscopic
life, aging also permits the loss of excess quantities
of gases and the precipitation of toxic minerals
sometimes present in new water, especially water
from wells and springs.
Conditioned water is water which has supported
fish life. It has been demonstrated that at least under
some conditions fish grow better in conditioned water.
Most aquarists already recognize the importance of
this phenomenon for it is a common practice to add
at least some "old water'* to a newly estabhshed
aquarium. It is not yet known what is involved in
conditioning. Perhaps the best theory to date has
been offered by Breder (1931). He suggests that
water previously occupied by fishes contains a
bacteriophage that controls the growth of undesirable
bacteria. Other possible explanations of conditioning
might include changes in the ionic system of the
water brought about by exchanges of salts between
the fishes and the water, or we might say that in the
presence of fishes the ionic system of the water is
adjusted to more nearly suit that of the fishes' requirements. Also relating to the ionic system is the
possibility that toxic ions are absorbed by the first
fishes and thus leave the water more favorable for
the subsequent inhabitants.
Under the heading of "Polluted Water" it is necessary to recognize a number of subdivisions. It will be
MAINTAINING FISHES
been utilized by fishes but has been permitted to
stand long enough to develop a population of microscopic and semimicroscopic plants and animals. Sunlight and the addition of a small amount of organic
matter result in more rapid and complete aging. In
addition to involving the development of microscopic
life, aging also permits the loss of excess quantities
of gases and the precipitation of toxic minerals
sometimes present in new water, especially water
from wells and springs.
Conditioned water is water which has supported
fish life. It has been demonstrated that at least under
some conditions fish grow better in conditioned water.
Most aquarists already recognize the importance of
this phenomenon for it is a common practice to add
at least some "old water'* to a newly estabhshed
aquarium. It is not yet known what is involved in
conditioning. Perhaps the best theory to date has
been offered by Breder (1931). He suggests that
water previously occupied by fishes contains a
bacteriophage that controls the growth of undesirable
bacteria. Other possible explanations of conditioning
might include changes in the ionic system of the
water brought about by exchanges of salts between
the fishes and the water, or we might say that in the
presence of fishes the ionic system of the water is
adjusted to more nearly suit that of the fishes' requirements. Also relating to the ionic system is the
possibility that toxic ions are absorbed by the first
fishes and thus leave the water more favorable for
the subsequent inhabitants.
Under the heading of "Polluted Water" it is necessary to recognize a number of subdivisions. It will be