I have 9 harlequin rasboras and 9 Pygmy cories in a 20 gallon tank with an aqua clear 50 HOB filter. It’s somewhat planted and should have plenty enough hiding spaces. Water parameters are 0 ammonia and nitrite and 20 nitrates. The ph is around 7.5. I do a 50% water change every week and gravel vac the surface of the sand every time. I feed them every night with the light on and unplug the filter, however they don’t always eat and they won’t eat until the hikari micro pellets start to sink. The harlequin rasboras don’t colour up much at all and tend to sit still, sometimes at the back of the tank and sometimes at the front. Is this just how they are or am I doing something wrong? I am really struggling to figure out why they do this.