I have one discus that I bought a sale at petco and I absolutely love him. I was thinking about buying 3-5 more as I know they do good in groups. Would it be a good idea to buy them all from the same place or does it not matter? I would kind of like a mix of all different types but am not dead set on it. Is there a good number to group them in? They will be going in a 75 gallon tank for now.