Betta becoming more aggressive?

Hi guys so I’ve had a planted 10 gallon tank with 1 male betta and 5 neon tetras for about a year now. The betta was always very chill and all the fish kind of kept to themselves until a few days ago when I moved. I took all the fish out and put them all in a little container for about a day. They were visibly stressed from the loss of movement and color, but they all made it and now they are back in their redecorated tank. I kept all the bb wet so the cycle did not crash and there was a lot of water left over in the tank for the plants and bb on substrate to stay alive as well.

Anyway, it was fine for the first 2 days but this morning my betta was chasing around all the tetras relentlessly. He was flaring his gills all the way out and trying to nip them (something I’ve never seen him do before). One of them finally turned around and nipped his fin back. The betta gets tired and then starts up again. The neon tetras don’t bother him until he starts to chase them.

What caused this behavior? How do I make it stop and go back to normal? I have a running cycled 55 gallon tank that currently has no other fish in it (my goldfish did not survive the move as the person who was in charge of feeding her dumped the whole container of food in her bucket) should I just separate them for good and put the neon tetras in there? I would like to keep them together if I can.

 

Hmmm...This is odd. I think he just kinda snapped all of sudden. AcornTheBetta Betta'sAnonymous FishGirl115 , maybe you guys can help.

 

May never know the "why" other than the fact there is a betta involved. Stress, maybe he just got tired of them always being around, etc. I would seperate them myself. Remember, a lot of times with aggressive types of fish, the question isn't "if", but "when".

 

Weird. The only thing I can think of is that he's trying to claim his territory now that it's redecorated. I don't know how you'd fix this. I've actually given fish time outs and it's worked. I've just netted them and rested the net from wall to wall on the tank and leave them there for 20-30 minutes then release them.

 

I think keeping him in a breeder box for 2 days will solve the problem.

 

I have heard that when bettas become stressed they become more aggressive. I would try and separate them temporarily.