It's because of all the predatory birds flying around your house. I mean, if you're a Discus and you go out into the light, they can see you and eat you. They need a little time to figure out it's safe to go out, because the New Zealand diving fish hawks just aren't sitting on that railing looking down at the tank.
You can't blame them for being wary - Amazonia is a tough place.
if you have something like Monstrera above the tank light strip, with those big leaves, they don't care about the brightness because they see cover. They'll come around. Instinct kicks in, but they learn.
You can't blame them for being wary - Amazonia is a tough place.
if you have something like Monstrera above the tank light strip, with those big leaves, they don't care about the brightness because they see cover. They'll come around. Instinct kicks in, but they learn.