I have 25 in a 1.25 gallon tank and 60 in a five gallon. There are times when there is little activity and others times when many are swimming about. At one half inch a few more will not hurt. They are very active when being fed and I believe many videos are taken at that time. How often do you feed them? Do you have any snails? I think snails are useful. 10 MTS type snails would be fine. I also use the honeycomb rock in my 5 gallon. The more hiding places the more they seem to hide. My 1.25 is more open and active.