How do you light your aquarium? Do you use natural light? A lamp? An aquarium light in the hood that covers your aquarium? Or some other way to light your fishes’ living space? What’s the best way to give your fish a lighted living area?
You want to recreate the natural habitat for your fishes. There is a day/night cycle that is important for fish. There’s got to be a balance, because, for example, consider how you would feel if you had to live day and night under a bright light or in darkness! Stressful, either way … right? Yes.
Without normal day and night conditions, we’d all be unhealthy and unable to enjoy our normal behavior patterns. Inside your house, these conditions don’t exist unless you create them for your fish.
You’ll need lighting intended for aquariums to give your fish the natural wavelengths present in normal daylight. Placing your tank in direct sunlight doesn’t work because it overheats the water.
For the night cycle, remember that even in natural underwater habitats for fish, it is not completely dark. It’s usually gently lit by moonlight. Lunar LEDs are the best source of a dim light for your fishes’ nighttime rest and your observation of your dear fish.
Use a lighting timer so you don’t forget and in case you’re not there to maintain the daylight/moonlight conditions.
Depending on the type of fish you keep, (that is, depending on what their natural environment would be like as far as how it would be lighted), you may need either less intense day lighting (as those fish who would in nature come from a rainforest river), or your type of fish may need high light (for example, fish who normally would live in shallow, tropical areas), or they could need “actinic light” (such as for deep water fishes.) These are not very intense and they appear blue.
As a quick reference: For bowls with low-light organisms you may want an incandescent/halogen bulb; for freshwater fish in shallow tanks you could use a normal output fluorescent bulb; with freshwater planted, nano reefs, saltwater fish only you may utilize a high output or very high output fluorescent bulb; for anything it’s possible to just use a power compact fluorescent bulb; and for coral reefs, high light organisms, and lighting that is best for plants - get metal halide and HQI lighting.