Sudden death of chick

[JellyrollBrahma]

We just hatched out some chicks 2 days ago. We kept them in the incubator after they hatched as we have done several other times beforehand, as we waited for the rest of the chicks to hatch. Last night, there was a chick a day old that was totally fine and then when I woke up, I looked in the incubator and it was on it's belly with it's eyes closed gasping like it was suffocating. I opened up the incubator and picked up the chick and saw that there was gooey fluid in it's mouth while gasping. It convulsed and died in my hand within 1 minute of holding it. When I set it down on a paper towel, I saw a big glob on the side of it's beak that was clear/cloudy. I poked it with a q-tip and it was thick.
The rest of the chicks that were with it both last night and today look fine. This chick was the only one (so far) who's dad was a Brahma. The rest of the chicks had an Australorp dad.
What happened? How do I prevent this again?

 

[birdsrfun]

Sounds like you have experience hatching chicks. Sometimes, chicks just die for unknown reasons. It may have suffered trauma during the hatch. Sorry for your loss.