Aquarium Lighting for Mollies


2015-09-13 female spotted mollyIn the wild, most mollies live in warm streams. When raising mollies in captivity, it’s important to attempt to recreate this environment. Lighting should keep water warm, between 77 and 82 degrees Fahrenheit. It should also only be used during specific times, providing a night and day effect. In general, the best lighting for mollies is dependent on the type of aquarium you have, as well as whether or not your aquarium contains live plants.

Types of Aquarium Lighting

In general, mollies will do just fine living under the glow of basic fluorescent lighting. If your tank contains live plants, you’ll want to opt for fluorescent lighting tubes, which promote plant growth.

Aquarium plants also thrive under the light of metal halides, but these powerful lights generate a lot of heat, so they may not be optimal for your mollies. Metal halides may overheat the water when they’re left on for hours each day. For aquariums, with depths less than 16 inches, opt for power compacts.

Lighting Schedule

Create a daytime effect for your mollies by leaving aquarium lights on for 8 to 12 hours a day. To make things simple, pick up a lighting timer from your local pet store. The timer can be programmed to turn lights on and off at specific time intervals. A timer ensures you won’t leave lights on for too long, which could potentially cause a spike in algae. Keep a thermometer inside the tank to ensure lighting is keeping the water a warm 77 to 82 degrees Fahrenheit.

Lighting a Fish-Only Aquarium

For fish-only aquariums, a single watt of lighting per gallon of water is all you’ll need. For very large tanks, those that are 50 gallons or more, you’ll want to increase the wattage to ensure that all depths are heated. It may be a good idea to fully submerge a thermometer, ensuring that you’re measuring the temperature of the bottom of the tank and that it’s warm enough for mollies.

Lighting a Planted Aquarium

Mollies thrive in aquariums that feature living plants. Plants are going to require special lighting to ensure growth. Plants will feature packaging that details the type of lighting preferred for optimal growth. In general, you’ll want to apply 4-6 watts of lighting per gallon of water in a planted tank. Depending on the depth of your tank, this wattage may need to be increased or reduced. Like mollies, plants prefer natural lighting. Light spectrums between 5500k and 6500k closely resemble the light produced in the wild and should work well for mollies residing in a planted tank.

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