THE AQUARIUM BUILDING
1/
cost of construction, the use of a glass roof, at least in
northern latitudes, should be avoided until there is
more evidence that such a roof is of particular benefit.
In this connection it is w^orthy of note that large tanks
that are constructed largely of opaque materials wiW
require more light than small glass aquaria to give the
same results. In direct sunlight glass aquaria become
unmanageable as a result of the excess growth of
algae.
Perhaps the soundest basis for calculating the
amount of artificial hght for an aquarium room is to
determine the average amount of natural light in the
room on a clear day and then adjust the intensity of
the artificial hght to simulate this value. Such an approach should result in the artificial hght being suGBcient to e£Fectively "extend the day." Perlmutter
(1962) has shown that fluorescent hghting reduces
the viabihty of trout eggs. Incandescent bulbs should
therefore be used. They may be controlled by inexpensive time clocks sold by many dealers in poultry
supplies. If algal growth becomes a problem, it may
be necessary to cover or to curtain portions of glass
aquaria or to screen out part of the natural light and
of course correspondingly reduce the intensity of artificial light.
There is more than one approach to deciding the
period of illumination to be used. In their native
habitat tropical fishes are exposed to 12 hours of daylight throughout the year, whereas temperate zone
fishes are exposed to seasonal increase and decrease
in the length of day. Tropical fishes probably fair best
with a constant 12-hour day. The situation for temperate-zone fishes is a bit more complex. It is probable
1/
cost of construction, the use of a glass roof, at least in
northern latitudes, should be avoided until there is
more evidence that such a roof is of particular benefit.
In this connection it is w^orthy of note that large tanks
that are constructed largely of opaque materials wiW
require more light than small glass aquaria to give the
same results. In direct sunlight glass aquaria become
unmanageable as a result of the excess growth of
algae.
Perhaps the soundest basis for calculating the
amount of artificial hght for an aquarium room is to
determine the average amount of natural light in the
room on a clear day and then adjust the intensity of
the artificial hght to simulate this value. Such an approach should result in the artificial hght being suGBcient to e£Fectively "extend the day." Perlmutter
(1962) has shown that fluorescent hghting reduces
the viabihty of trout eggs. Incandescent bulbs should
therefore be used. They may be controlled by inexpensive time clocks sold by many dealers in poultry
supplies. If algal growth becomes a problem, it may
be necessary to cover or to curtain portions of glass
aquaria or to screen out part of the natural light and
of course correspondingly reduce the intensity of artificial light.
There is more than one approach to deciding the
period of illumination to be used. In their native
habitat tropical fishes are exposed to 12 hours of daylight throughout the year, whereas temperate zone
fishes are exposed to seasonal increase and decrease
in the length of day. Tropical fishes probably fair best
with a constant 12-hour day. The situation for temperate-zone fishes is a bit more complex. It is probable