I am by no means an expert, but 4 work together great in both my tanks. Most people will say minimum of 5 or 6, but 4 works for me. Plus, it still follows the 10 gallon per fish rule. 5 didn't work in my tank. 2 bullied the other 3 and each other until I sold them and got a new 4th. I have never heard anything good about only keeping 3 together.Looks like April has an awesom shipment coming in! I will deffinatly be contacting her.
I realy wasent sure how many I could get in my 45, I would love to get 4 if you think there wouldent be any problems.