Fish and Light ?

[chris de meo]

Do fish need light or are they ok with a lid on the tank? ie in the dark ?? i have seen many opinions on this ... i currently have lids on my tanks with only small light source where the water supply enters ...

Cheers 

[Keith Rowan]

ohio state did a study that showed "optimal" growth with an cycle of 18 hourse light 6 hours dark had the best performance in either yellow perch or bluegill..i can't find that doc at the moment..but here is a different one that says yp exposed to 16hours of light have best growth..

this study shows how the light cycle was used to induce spawning in yp

http://www.extension.org/mediawiki/files/b/b6/Evaluation_of_off-sea...

[Jon Parr]

Fish need only enough light to determine day and night, and do not benefit directly from bright light.

[chris de meo]

thanks guys looks like i have a fair idea of what to do ....cheers 

[Alex Veidel]

It depends on the fish of course, but light actually has a tendency to stress fish out, at least for tilapia. Fish that are not carnivores or in their natural habitat have a tendency to be hunted feel secure in the dark. Its usually best to limit light exposure, plus it helps keep algae from growing and competing with your plants for nutrients.