Originally Posted by RussellTheShihTzu
Welcome to the Forum!
Betta are territorial fish plain and simple. Some more so than the other; some have bigger "territories" than others. They chase other fish out of their territory because that is what they do and how they establish the boundaries of this territory.
Cory/Catfish and others occasionally zip to the surface. Some Betta ignore this temporary intrusion; some do not.
What is the GPH of your filter? Is the tank well enough oxygenated for non-labyrinth fish? I am sure it is but sometimes owners maintain a low-flow-oxygen-level that is fine for Betta but not for those with only gills. So gotta cover all the bases. This zipping to the surface, if frequent, could mean you need more oxygenation.
One way to tell if the tank is oxygenated for all the residents is to note if a Betta frequently breathe from the surface or makes use of its gills and seldom surfaces. I cannot recall the last time I saw one of the Betta in my community tanks surface breathe.
I would not give up on the Betta just yet. Chasing something new is perfectly normal. In 40+ years of Betta-based community tanks I have had fewer than 10 (actually, I can only think of five) that did not settle down after a week and ignore the other fish. Those guys who had to live alone aggressively and relentlessly chased other fish all over the tank or stalked one particular individual from the get-go. They were in another tank faster than you can blink an eye.
Ohhhhhh I hadn’t even considered the oxygenation. As a betta girl, and never a giant 20 gallon for one fish girl, oxygenation wasn’t even on the thought train. They don’t zip up to the surface a lot, but, they’re zippy though! Honestly I’ve experienced way more joy in owning those little fellers than I expected of a fish considered primarily “clean-up”. I did go home and provide a lot more cover and everyone seemed super chill about it and happy. I watched them for a bit and then had to leave when I was comfortable with the behaviors. As far as my filter flow, I’m honestly not sure (and I can’t say for sure until I get home). I got the actual mechanism when I purchased the 20g but never throw out any kind of manuals so I still have the info. But again, as a betta girl, the lower power output the better, so it’s probably not moving fast enough for any kind of oxygenation.
Swim Shady: doubletail male
Ella: veiltail female
Neo: crowntail male
Bruiser: crowntail male
"When you see a fish you don't think of its scales, do you? You think of its speed, its floating, flashing body seen through the water... If I made fins and eyes and scales, I would arrest its movement, give a patter or shape of reality. I want just the flash of its spirit" ~ Constantin Brancusi