I currently have 1 angelfish and 3 guppies in my 10 gallon tank. I keep reading about how everybody loves the little cory catfish. If I added one to my 10 gallon, would I be overtsocked? If yes, I plan on getting a 5 gallon in a month or two for a betta for my new office. Would a cory and a betta be ok in a tank together?