Aquarium Light -
Aquarium Light
Light is necessary for the successful maintenance of tropical fishes. Just how much light, the quality of the light, and the direction from which the light comes is matters for much speculation.
The amount of light necessary is a variable that is not always easily controlled. Direct sunlight for any extended period of time is not beneficial to fishes or to plants. A northern exposure is ideal for an aquarium that does receive any artificial light, though artificial light will provide light just well.
Fishes need light in order to see. Sight is an important factor in reproduction and in feeding. Plants need light for other reasons. Studies have shown that the intensity, amount (in hours), and quality of light have important effects upon reproduction in certain fishes. It has been demonstrated that in the medaka, Oryzias latipes, light periodicity has a positive effect on ovulation. If kept under continuous light, guppies will have broods every 3 weeks instead of every month. Yet in the killifish, Fundulus, no positive effects from changes in light periodicity were found.
Light has a definite effect on the colour of fishes. A simple example is to view fishes that have spent many generations in lightless caves. These fishes, such as the popular blind cave characins, are lacking entirely in pigment.
Ordinarily, fishes are diurnal and need about 12 hours of light per day. The intensity of light must vary with the size of the aquarium, and a few practical experiments will easily show just how much light is necessary. An allowance of about 2 watts per 5 l of water is ample for an aquarium hood light. In smaller aquarium the problem of overheating owing to the use an electric light must be considered. During the summer when there are 15 hours of sunlight these fishes do not how any adverse effects.
If leafed plants grow well in an aquarium, then the aquarium is receiving enough light. Too much light usually causes Green water, water that is filled with green plankton. To rid the aquarium of this unpleasant condition it is necessary to remove the fishes and place dark paper all about the aquarium. Add some live Daphnia to the aquarium to eat the algae. the use of taller aquatic plants also aids in keeping water from becoming green.
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10-18-2005, 05:57 AM
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