:I i gotta disagree. all of my bettas have lived in plain sight of each other. right now, i have Ichi, Sniper, Lulu, and Spy, side by side. Ichi can see Sniper. Sniper can see Ichi and Lulu, who can see Sniper and Spy, who can see Lulu. between those four, none are stressed at all. as long as you give them plenty of plants to hide in, to get away from each other for a while, they're fine.
shoot, Sniper and Ichi see each other all the time, only hiding once in a while, and they don't even flare anymore. before they passed, Medic and Josie found comfort, almost, in each other. Medic stopped her glass surfing after i put Josie beside her, and started watching Josie...
and before he died, Theo and Ichi lived side by side, in constant view of each other, and i never had issues. because of Theo's blindness, he showed no aggression to Ichi, and Ichi would sit and watch Theo do his thing. never had any issues with Ichi tail biting before Theo died, in fact. it wasn't until i removed Theo's tank after he passed away, that Ichi ever started tail biting. and since putting him in sight of Sniper, he hasn't nipped since.