Question: Strange death and advice needed :(?

[AmyD]

I previously owned a yellow axie and kept him under the same conditions, he was very healthy and I had him for over a year, however out of the blue he started to turn a little reddish and had slightly swollen bum, but he seemed fine - eating normally and doing the usual stuff. Then I looked in the tank and he was pale white floating (dead) and it look as if his bum exploded (mind the crude explanation) there was dry blood around his bum and what looked like innards floating on top of the tank. I instantly removed him to avoid my other axie getting ill.
Does anyone know what could have caused this and how he died?

Also

Whenever I get two axolotls one seems to die it has happened twice before. I owned a Black axie- amigo for a year and I got Lindo the yellow one about 3 months after him, they where fine but out of the blue Amigo died and Lindo was fine, then I had Lindo for over a year and I got Pach'ua my newest axie about 2-3 months before Lindo's mysterious death and Pach was fine and I still have him and have had him for over a year and a half. I want to get another one to keep my Pach company but I'm worried i'll loose him . What should I do ?

 

[axolotl newbie]

That sounds horribly traumatic Hope you're ok.

Just wondering if you have gravel or anything in your tank which your axie could have swallowed and died whilst trying to pass it?

 

[Kaysie]

What kind of substrate are you using? Sounds like a severe prolapse, especially coupled with red and floating.