Sundance (Elephant Ear Betta), Johnny (Guinea pig), Kooky (Guinea pig)
Poor fishy...I'm sorry for your loss. I hope someone here can determine at least an idea of what happened. I mean I don't know much but from your info it seems everything was alright. That level of ammonia isn't great but not fatal. My tank is like that right now because of new substrate and my boy is fine. So sorry about your baby.