I rescued him from a girl I used to work with she didn't take care of him properly and got very sick and she was going to flush him. So I brought him home bought him a 5 Gal tank and began trying to save his life.
Don't get discourage though, don't get upset it really happened a lot in the fish world. Well all animals get sick just like human being . It just circle of life. Just think this way , you do rescue a life from the terrible store and give him your love. So i wish you will do it again. And i hope to talk to you again. May be we can figure out what happened. And i think you need to disinfect the tank if he was in the separate tank. Let me know if you need any help, i hope to talk to you again. Thank you .
Sorry:( If you can give me more details we might can figure out if it either may be you have to change the way you doing something or if he was sick to begin with. Also not sure if you had him in the same tank with other fish? Bettas i think more fragile , more susceptible to the disease then other fish . I saw so many post when betta is sick but all other ones are doing great. Not sure if you had him in the same tank, but i think it really better for betta to have his own tank to prevent any infections.
He passed away...I was so upset. I bought a new one my granddaughter named him squidward lol. I also got with 3 male Guppies. They are doing great, except 1 or 2 of my so called male Guppies look pregnant.