I lost my little plakat very quickly overnight. Yesterday afternoon as I was doing a water change I noticed he was looking bloated and laying on the bottom of the tank. The day before he was perfectly happy and active. Within an hour he was losing colour. I put him in a smaller bare tank with some aquarium salt, if anything just to make him comfortable whilst I worked out by next step. It was getting late so I left him overnight but this morning found him grey, stiff and covered in a white fuzzy looking film that wasn't there yesterday :-( I didn't take any photos. Now my 2 other bettas that share a divided tank are looking a little bloated. I don't think I overfeed them but then again I've been a bit migrainey the last few days and may have been carelessly giving them more pellets than usual. I'm terrified I will lose them as well to whatever killed my plakat. Any thoughts on what this could be? I would give water parameters but I must admit I've been slack with this recently after keeping betta for almost 5 years and dealing with chronic headaches for the last 2, these days I only test my water when I notice something wrong. I can test the water from the deceased fishes tank when I get home from work in 10 hours. Aside from this my tanks are 38 litres, I change 50-75% of the water once a week using a vacuum and Seachem Prime, I keep the tanks at 27°C and feed my bettas pellets twice a day.