SdJaCK&SaLLy

- Light is necessary for the successful maintenance of tropicals fishes. Just how much light, the quality of light, and the direction from which the light comes are matters for 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 not receive any artificial light. will provide light just as well.

- Fish need light to see. Sight is an important factor in reproduction and 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 fish. It has been proven that in medake ( Oryzias latipes ), light periodically has a positive effect on ovulation. If kept under continuous light, guppies will have broods every 3 weeks instead of every month. Yet Killifish, have no positive effects from changes in light.

- Light has defiant effect on the color of fish. A simple example is to view fish that have spent many generation's in lightless caves. These fish such as the popular Blind Cave fish, are lacking entirely in pigment. Ordinarily fish 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 needed. An allowance of about 2 1/2 watts per gallon of water is ample for an aquarium hood light. In smaller aquaria the problem of overheating owing to the use of an electric light must be considered. Fish maintained in northern parts of the world will need artificial light during the winder month.

- During the summer where there is 15 hours of sunlight these fish do not show any adverse effects.

- If leafed plants grow well in an aquarium, then the aquarium is receiving the adequate amount of light. Green water, water which is filled with green plankton is usually caused by too much light. To rid the aquarium of this unpleasant condition it is necessary to remove the fishes and place dark paper around the aquarium. Add some live Daphinia to the aquarium to eat the algae. The use of taller aquatic plants also aids in keeping water from becoming to green.