I have a 10 gallon freshwater tank for 2 months with 2 zebra danios and 2 mickey-mouse plattys. Last water change was a little over 2 weeks ago. I just vacuumed half the tank, scrub the decor, and changed about 40% of the water but about 15 minutes later I look over and one of my danios was freaking out! A minute later it started to float to the top upside down struggling around the tank and 5 minutes later it completely stopped moving and got stuck to the filter. Once i gave it a nice funeral my other danio started to freak out too but chilled out after a few minutes. My plattys are alright but they do seem a bit slower than usual, what did I do wrong? Sorry this is so long but I love my fish so much