That is helpful! We are planning a water change later- and we can absolutely use water from other tanks. At the moment, the tank I’d usually keep Kestra in is going through “upgrades” so only live rock, corals and clean up crew are in that one. The plan was to move them both (Odo and Kestra) into larger tanks when they get big enough.Not crazy about the waterline hang out but DON'T change a bunch of water. I don't have a formula for best practice when they are this small, it is still kind of hit or miss. It is anecdotal but both Steve O'Shea (squid not octos) and I both noticed that hatchlings and juveniles did better in older, less pristine water. I would even suggest using the water you take off from the other octo tank to do water changes in this one if you need to change out water because of waste. Wish I could be of more help.
That is certainly our hope, that it’s just in a rock being shy! Only time will tell, so we’ll just keep up with maintenance and wait for the tax return so we can get some Kessils for growing ricordea and zoanthids.Odo was so young it is hard to make any kind of call. Best case (and quite normal) is that she/he is holed up in the LR. Be sure you keep plenty of small crustacians (pods and hermits and you might try keeping some live shore shrimp in the tank). Worst case, she/he was so small that death did not disrupt the tank. Experience makes me tend toward the first guess. They typically stay hidden until around 5 months old.