Apparently the longest ever recorded glide is 45 seconds.

Fish don’t have lungs, so the analogy is kind of busted, but some humans can hold their breath for 30 seconds, some 2 minutes, some 5 minutes, but overall it doesn’t take long for brain damage/death to occur.

I’d guesstimate that a flying fish would be probably irrevivably dead after 3 to 5 minutes out of water.

I tried to look up more specifics on flying fish respiratory systems vs other fish back when I posted this, to see if they have measurably better ability to remain alive out of water for longer than other fish, but I couldn’t find much.