Male Betta behavior

Question
Hi! I wanted to ask your opinion about male Bettas. I've been told it is awful for them to be able to see each other at all.  I've been thinking about putting my 3 males in a divided tank where they can see each other but not touch, but I don't want to cause them stress or make them unhappy.  All 3 are young males (between 3 and 4 months old). What is your opinion or experience? Thanks in advance!

Answer
I don't recommend it for several reasons. One being that yes, I do beleive it causes them stress, due to the fact that for the most part they will constantly be on guard, worrying that the other fish might try to steal it's "territory". (Which is reasonable of course, because the betta is very territorial - hence the name "Siamese Fighting Fish")
Another reason would be the fact that a divided tank will be much harder to clean, and much more stressful to the fish if you constantly have to move them in and out of the tank in order to do water changes safely.
Also, divided tanks will restrict aeration, and greatly shorten the amount of surface area, which is more important for a betta than most other fish, since they have labyrinth organs; through which they breath oxygen at the surface of the water. They have this organ because of the long, but shallow rice paddies they originate from in Asia where they have plenty of surface area but not much depth to the water. This fact is largely the reason for so many misconceptions about bettas - such as Betta's prefer "tiny bowls/tanks" and "dirty water", both of which are far from true.
I hope this has helped you in better understanding the needs of your Siamese Fighting Fishes! And please feel free to write back again if more questions arise.