I have a 20G heavily planted cardinal tetra tank. The tank has been up for 4 yrs and there were about 10-12 adult cardinals in it with red rummy noses. After the recent move, several cardinals and red rummy noses died by the move. All the remaining fish started keep hiding behind the plants.

I know they would thrill in numbers, so I bought another 30 small cardinals over the weekend. But they are still hiding behind the plants at most the time. How can I make them stay out at all the time n not being scared when I walk back n forth in front of the tank?

I also noticed the PH is at 7.0 is abit of high for cardinals, but they should of get used to it by now. There is a AC 50 running on the tank, could the water current too strong for them?

I had the same problem with my trop tank last year. I moved and had to place it in a hall with heavy traffic. After a few months I noticed all my tetras hid, I actually had people ask me if there were any fish in the tank (there are about 24!).

Moving the tank to a quieter location really helped. I also rearranged things a little. I know tetras feel safer when they have places to hide, but I made it so that they didn't have quite so many (I took out some rock caves, bunched some plants together, etc).

As for the current, I'm not sure. They are river fish but that may be strong, however I've never seen tetras mind a strong current too much...and with a heavily planted tank I wouldn't think that would be too much of an issue. The pH is a little high for them, maybe you should try to bring it down. Drift wood can do a great job of that.

I was thinking about the other way as to place the fish tank in a quiet location. All my fish spend day time by themselves since no one is at home during the day. That's why it makes believe that they are used to be in a quiet environment.

I went to one of my LFSs before and they have this 30 tall tropical tank with couple cardinal tetras in it. All of them were standing/swimming in front of the tank even though people were approaching to the tank or walking back n forth in front of the tank. I guess they are used to the heavy traffic in front of them everyday.

I feel I should figure out a way to have something moving around in front of the tank at all the time, so they can get used to it. So they won't go hiding whenever I'm approaching to the tank.