l8
MAINTAINING FISHES
that for work not involving attempts to produce natural spawning, the length of day should correspond to
the seasonal temperatiure at which the fishes are being
held. When one is attempting to produce a natural
spawning it may be necessary to systematically increase illumination for spring-spawners or systematically decrease it for fall-spawners. In connection with
the control of spawning one should consider the possibility of using pituitary hormones. (See section on
control of reproduction.)
Water Supply
TEMPERATURE: The breeding and holding of
fishes requires fairly accurate control of water temperature, and experimental conditions usually prescribe a
particular water temperature. Temperature characteristics of water are dependent upon the source. Well
water is in the 50° to 60° F. range and remains approximately the same summer and winter. Lake,
stream, and tap water are markedly affected by air
temperature, although water from a spring fed stream
and water from 20 or more feet of depth from a lake
have a stable temperature quite similar to well water.
In any case facihties should be available for heating
water prior to its use. For most installations a conventional gas or oil type water heater of high capacity
is the best choice. In many cases it is desirable to have
duplicate water supply lines, one for cold water and
the other for heated.
CARBONATE CONTENT: The minimal mineral
content of water does not usually constitute a problem
with the possible exception of the carbonate content.
MAINTAINING FISHES
that for work not involving attempts to produce natural spawning, the length of day should correspond to
the seasonal temperatiure at which the fishes are being
held. When one is attempting to produce a natural
spawning it may be necessary to systematically increase illumination for spring-spawners or systematically decrease it for fall-spawners. In connection with
the control of spawning one should consider the possibility of using pituitary hormones. (See section on
control of reproduction.)
Water Supply
TEMPERATURE: The breeding and holding of
fishes requires fairly accurate control of water temperature, and experimental conditions usually prescribe a
particular water temperature. Temperature characteristics of water are dependent upon the source. Well
water is in the 50° to 60° F. range and remains approximately the same summer and winter. Lake,
stream, and tap water are markedly affected by air
temperature, although water from a spring fed stream
and water from 20 or more feet of depth from a lake
have a stable temperature quite similar to well water.
In any case facihties should be available for heating
water prior to its use. For most installations a conventional gas or oil type water heater of high capacity
is the best choice. In many cases it is desirable to have
duplicate water supply lines, one for cold water and
the other for heated.
CARBONATE CONTENT: The minimal mineral
content of water does not usually constitute a problem
with the possible exception of the carbonate content.