I’ve raised 4 broods now. Regarding the airbubble you see. Don’t mistake the swim bladder for an airbubble. This is actually an airbubble, however the babies need it for bouyancy, and fill it when they are first born. I know it does look like they’ve injested air. They may have injested air though. If they are floating helplessly at the top they have injested air.
I found it was best to actually chop the mysis with a knife rather than try to chop it any other way. When converting them over though, make sure that you mix just a little mysis in with the artemia to give the artemia the smell of mysis. The babies will start recognizing the smell as food. They will make the switch much quicker that way. After you start seeing them taking bites out of the mysis it’s time to start weening them off of the artemia. You’ll be able to judge how fast for yourself by watching them when you feed them. Once most of them are recognizing the mysis as food you can stop the artemia. (and rest)
All it takes is for one baby to catch on, and your in business. Keep in mind though you may have a few that just don’t catch on for some reason, and they will not flurish. I don’t know why, but I’ve had a few in every brood that just don’t make the switch. 18 is a great number for your first brood. Are you thinking about a grow out tank yet? Or will you need one?
Good luck, and best wishes with you little ones. I can’t think of anything quite as satisfying as raising your own brood.