I woke up on this 4th of July and I went to feed my Betta and noticed his tankmate, Tina had died. I really don't want to test the water right now as it is clear and Blue is doing fine... I can rule out starvation because I saw that she ate as well when algae discs were dropped in and I want to rule out that Blue killed her because she didn't have any visible damage. This Oto had survived a whole lot and meant very much to me, she was what kept me inspired to continue through any tough times in the hobby just as she had done. I'll reply later with test results but the tank has been cycled for a while..