I just assumed that my baby died of a fungal/bacterial infection that we couldn't fight anymore. But I figure I should post what happened just in case. I don't know if it's relevant, but I'll post just in case. My little Blue (a blue veiltail) was bought at Parrots of the World in Rockville Centre, Long Island, New York. I don't know how old he was when we got him but he still had those big black baby fish eyes and was much smaller than he was when he died.
I had him for two years. When we brought him home, he was in a tiny little bowl that they sell them in. I got him a one gallon tank pretty quickly, but I still didn't know enough about betta fish to get him a heater until a few months later. I did know to change the water frequently and not use soaps or detergents and very basic things like that.
After a few months I noticed his eyes had started to protrude bilaterally. I used some basic fish meds like Betta Fix and that seemed to help. He would occasionally get little white patches, but the water-treatment antibiotics seemed to keep it at bay.
Then his fins started becoming affected. For the last year of his two year life I was constantly battling a condition that was deteriorating his fins from the edges, causing them to turn white at the edges and working its way towards his tail. Then the while infection got to his tail, but all the while he was still active and eating very well. I eventually moved on to more aggressive treatments like tetracycline, then erythromycin. The best I could do was keep the infection at bay for a while, but over time it kept getting worse.
Finally, after two years with me, my little friend stopped eating. I knew right away this was the end. No matter what had happened before, he always ate well, and begged for more. My little pal refused to eat and started hiding from me. He used to greet me whenever he saw me. I could be walking around the room and we'd both just be doing our own thing, but if I waved at him he would wiggle dance back at me. I loved him so much. It's been almost two months now and I'm still crying writing this.
The day he died, he was so pale and sick looking, I don't know if it's the kind of graying that you're talking about, but I figured I'd post it just in case. I don't know why, but for some reason I took pictures of him before I buried him. I'll include pictures of him alive that show the white infection when it had spread from his tail fins to his actual tail body plus ones of him after he died. The ones of him after his death may not be good quality because I was hysterical. I didn't even know why I was taking the pictures at the time, I just did it.
I doubt it is the same thing, but I wanted to help if I could. If I had known about this site before he passed I would have preserved him for you just in case, but I didn't and I buried him.
I'm so sorry for everyone who's lost or is losing their beloved fish friends. I hope we can find a cure for this.
PS: If anyone could tell me what happened to my Blue and what I should have done, I would really appreciate it. I never want my fish to suffer again when there's something I could have done. I've been trying to get better educated about proper betta care and learning about water quality and proper feeding and everything I possibly can for my new fish who I adopted from a Betta Rescue. I got her a couple of days ago and her abdomen is swollen, but I'll post about that in the proper area.