No, neon tetras are not more active at night. Neon tetras are schooling fish that are most active during the day. They require 12-14 hours of aquarium light to maintain a healthy circadian rhythm.
In addition, neon tetras need darkness to get a good night’s sleep and maintain a healthy lifestyle. They typically sleep huddled at the bottom of your tank with their eyes open.
Don’t be alarmed if some of your neon tetras lose their color at night, as this is normal behavior.