fish just jump out of the water for no reason sometimes...not so much neon tetras, but top-dwelling fish like swordtails, danios, and hatchetfish are known for jumping from the tank for no reason.
I have a closed tank, and between the lights and the water there is a glass brace.
One day lifted the lights and i found a backed neon on the brace.. :-(.
So even if the tank is closed if they realy want, they can commit suicide.
I've had a lot of different fish in my open top tank but the only ones I've ever had jump were my neon tetras. Odd little things, only jumped at night.
Yeah, some fish jump because they like to jump. Some salmon will jump straight into your boat, I am pretty sure they don't want to be eaten but they jump into your boat. They must be thinking "I did not think this through".
I've heard it said that the only fish that wont jump is a dead fish.
Even plecos and puffers have been known to bail if given the chance. Even if their behavior isn't suggestive of jumping, they certainly all have the ability to, and should be treated accordingly.