So i have a 20 gallon with my ranchus. I also had about 10 minnows in the tank with them. All of the sudden, the water got really cloudy and i did a water change and i found out all of the minnows except one are dead. Once i move the ranchus to the 40 gallon, i will probably get some more minnows for the 20. I am sad that most of my minnows died .