Hi just today all my fish including flying foxes and mollies and barbs have started spending a lot of time at the surface i did nit and ph tests and they are all normal mine is acommnuity tank planted. On top of this last night one of my minnows died after losing his colours and this evening one of my odessa barbs just died iimmediately did a 20 percent water change and they all seemed to settle again but now they are all at the surface again can any one help me thanks stefish