Hey Everyone , I've had my tank for close to around 5 months , and everything was always fine started with a beta fish and 6 harlequin Rasbora's and some catfish. Usually I do 10,20,50% water changes depending on the need but yesterday I did an almost complete water change because the gravel was extremely dirty. When I acclimated them and put them back in they were fine, however this morning the Rasbora's are at the bottom in a school not moving and my better is just resting in a rock I have. Did I do something wrong ?