Quick update on the octo-nursery:
I was out of town for a few days, and just got back tonight. I wasn't sure what I'd find, since the population has been decreasing.
As of about 11:00, when the babies are usually out on the glass and active, I hadn't seen *any*. I know that when I flash the camera, they typically perk up or wake up, so I tried a few flashes. Sure enough, one little guy came out from hiding. He is significantly larger than any I saw last week, and also very active. I'm almost certain that it's the same one that I noticed was particularly large and active last week as well, but he's really big now. No sign of anyone else still alive in the tank. Either they are all victims, or they are very good at hiding to avoid victimhood.
Because the babies just seemed to be cannibalizing each other anyway, I thought it would be worth trying to ship a couple to another TONMO member who had contacted me a while ago. My plan was to catch a couple tonight and ship them out tomorrow, so it's so disappointing that there weren't any potential travelers to be found. I looked in the sump, but there is so much live-rock rubble in there that I'd never find any even if they were still alive.
BUT then I decided to check the sock filter... I had never actually put any babies in there, and the slots for the overflow have been covered with a fine mesh since before the hatch. I had put a couple of small, cavernous pieces of live rock in the sock as a "blast shield" from the firehose-like overflow water. I pulled the sock out, put it in a bucket, carefully removed the rocks, and sure enough there were three little guys crawling around, looking quite healthy. There were also several amphipods running around on the rock, so perhaps the little octos have been eating. These three aren't as big as the "top dog" octopus that's running around in the main tank, but not observably smaller than the typical baby from last week.
So now I've got two little babies in one isolation tank, and one little baby with its cavernous rock in another isolation tank. (It's possible that the rock is housing somebody else too who didn't come out). Both isolation tanks are sitting in the main tank; just a small-sized critter keeper with nylon panty-hose stretched over the top and then the normal top attached over that.
I'll bag them up tomorrow (individually), give them lots of water and oxygen, ship them overnight and hope for the best.
Edit: Sure enough, there was another little guy living in the rock. So there are two babies in each isolation tank.