You guys are going to think I have way too much time on my hands but....I have been watching my discus several times a day, everyday (aren't you surprised!). I have discovered, if you pay attention, they tell you when the water needs changed. With my observations I noticed that in the first half of the 24 hour period, they stay almost exclusively in the bottom 3rd of the tank. They never go above it. In the 3rd quarter they are pretty much mid tank. In the last quarter before water change time they are in the top half and rarely go below the mid point in the tank. It is this way at feeding time too. I have mixed up the order they get their foods just to make sure it wasn't because they like this more than that and are up higher because of it. During the water change they sort of hide in the tops of the plants, but not to where I can't see them. Within minutes of the water change they are back down to the bottom third of the tank and stay there. This is every day. I have been taking note for about a week. At first I thought I was just imagining it, but I am not. So now I know that if I look at my tank before it's normal water change time and they are up high....go ahead and change the water.
Just thought I would share.
Just thought I would share.