Help 3 Dead No Known Cause

[aluno]

hi, about 3 weeks ago i found my betta male dead in my tank and he lived with 8 platties and a pleco who had stripped him of his beautiful fins, i didnt think anything of it then last week found a platty male dead in the tank then today i wake to see my female platty floating, as the pic shows there doesnt seem to be anything out of the ordinary except i noticed she had some red stuff comming out of her so i squeezed her a little and it seems like blood and some white stuff,
checked the water today and ph was about 8 but has always been high and they never seemed troubled before, nitrate was 10 nitrite was 0 and ammo was 0.25 but i assume the fact there was a dead fish in there for a few hours might have started something
did a 30% water change.
any ideas guys
thanks

 

[Colin_T]

It could be a bad case of intestinal worms or an internal bacterial infection. Without doing an autopsy it is difficult to say for sure but livebearers like platies are renowned for worm infestations. Perhaps try treating your fish for intestinal worms and see how things go. Otherwise take the body to a fish vet and have it autopsied. You will have to take it there asap and it will cost a bit but it will give you more info on what killed it.

Personally I would just treat the tank for worms and see how things go