RIP little fishy :(
He came out of the rock work and was swimming around off and on, still foraging, after I wrote my last post.
I checked my water about two hours ago and my levels were actually quite good (which surprised me given my lack of sump and over feeding). Free ammonia = 0, trites = 0, trates = 10.
Given that my water wasn't as bad off as I anticipated, I decided to go ahead and try to set up the sump. I've been working on getting it up and running for the last hour and a half.
Fishy was still out and about when I checked my water levels, but when I went to put my HOB back on after securing the hose, I found him upside down in the rocks, obviously gone :(
I've called live aquaria and they have credited my account. I asked if they could send me another with the order of snails (which is supposed to ship on Monday), but they weren't able to. Probably for the best, as I suspect a new singleton would be bullied and might not make a good transition into the group.
I'm pretty sad to have lost my first fish, but I am relieved to know my water levels remained good and that it was probably something he had when he came and then got stressed being bullied. The remaining two are different sized, and little one hasn't seemed stressed at all, so I'm hoping they will both live long and happy lives.