It's not the number that counts really it's how many you want and how many the tank can handle with your maintenance. I have over crowded fry tanks that I have to do almost complete water changes on once a week and other growout tanks that have had all the males pulled from and only have 8 or 10 females left in a 20 gallon tank. They could be left for weeks with an occassional partial water change. The more caves, rocks, plants or whatever hiding places you have, the better they will get along. With a good filter system and weekly water changes and a good maintenance regimen you could have 8 to 12 in a 10 gallon. I spend half my day in my fish/bedroom tending to my 1,500 or so Bettas. I don't expect someone else to spend that much time nor would I recommend someone have 40 or 50 half grown Bettas in a 10 gallon tank like I do. It's all about how much time you personally have to take care of your fish. If you only have time to feed them once or twice a day and one day a week spend a half hour cleaning filters and changing water then go with a half dozen in a 10. The more fish you put in your tank the more time you spend keeping it clean and keeping your fish healthy.
Thanks. I think I will go with 7-8. I'm meticulous about my tanks. It's what I do in the evenings while the hubbs plays video games! If I post a pic tonight, can you all give me feed back on my setup? Whether I should add more hideys, plants, etc?
Really it all depends on the personalities of the fish you have. I've had as few as 4 in my tank at a given time (Daiquiri was in time out for a while), and they've gotten along just fine. However I've heard other stories from other members that have more aggressive fish. Really, you'll learn what works best for YOUR fish based on your experience with them. Don't expect to get it perfect the first time, something is always going to go wrong, just be ready for it when it does.