Woke up to a dead oto and one of the male guppies, who was also the smallest. All the other fish seem perfectly fine, energetic, and happy. All water parameters are fine:
Ammonia 0ppm
Nitrites 0ppm
Nitrates 20ppm
pH 7.8
As a side note the guppy who died also wasn't eating much. All other fish eating normal. My guess is he just didn't take good to acclimation