Sick Kubotai 1 dead 2 with symptoms.

Hi so I have a shoal of 12 kubotai rasboras. Had them for 4 weeks now and they’ve been absolutely fine. Water parameters are ph 6.5 and everything else zero.

Last week one of my kids spooked them and one jumped from the tank. I managed to get him back In the tank quickly and he seemed fine.

Next day he looked opaque (they’re bodies are usually glass like but now he had a cloudy whitish hue) and swollen. I put it down to his time on the carpet and kept an eye on him. Over the next 5 days he got increasing swollen and pine coned but was still eating. The swelling started to go down but then he then started swimming tail down for a day and died. The rest of the shoal was unaffected.

Yesterday I saw that another fish had taken on the whitish opaque appearance and was slightly swollen and I think another looks a bit cloudy too.

I feed daily but am gonna go every second day incase it’s over feeding. (I don’t think it is).

I’ve added melafix incase it’s a bacterial but I know it’s very hot and miss but I had it to hand and I don’t think it will do any harm.

Does anyone know what this might be? Obviously I’m thinking dropsy/bloat is the likely candidate but I’m blind to the cause.

The tank is well planted and there are Pygmy cories an Otto and lots of Neo shrimp that are all doing well.