I just want to thank everyone for their replies they were all very helpful. i have decided to keep him in his own tank as i purchased 3 female bettas tonight. I really don't think they should mix.
so thank you all!!! :)
i use pure melaluca oil on my betta which is the key ingrediant to melafix and ive never noticed a false reaction. betta fix and mela fix are the same thing but a different price. both of which are not all natural and have chemicals in them. i recommend you look into melalueca oil its much more effective and safer.