They've lived somewhat peacefully for months together in my 16G with an occasional run at one or the other. I have 2 female and 2 male cherry barbs in my with half-moon betta. My large betta took over one corner of the tank. Then just this week my large male betta is sitting on the bottom of the tank and I wonder if he just gave out from stress ? It doesn't look like anything is wrong with him. His color is off but that's it. I've had him since sometime in the summer. How long do betta live ? I honestly don't think he's going to make it thru the night and have no idea what to do about it. I put him in an isolation 1G bowl with just half a gallon of water so he could potentially reach the top, but I haven't even seen him try.
I'm thinking to put a sorority in there with the cherry barbs. Will that work ? Would it be better ?