Do fish die of heart attack?

Here is from the first paragraph of  “The Hitchhiker’s Guide To The Galaxy” by Douglas Adams.

“Far out in the uncharted backwaters of the unfashionable end of the western spiral arm of galaxy lies a small unregarded yellow sun. Orbitting this at a distance of roughly ninety two million miles is an utterly insignificant light blue green planet whose ape-descended life forms are so amazingly primitive that they still think digital watches are a pretty neat idea.

This planet has – or rather had – a problem which was this; most of the people living on it were unhappy for pretty much of the time. Many solutions were suggested for this problem but most of these were largely concerned with the movements of small green pieces of paper, which is odd because on the whole it wasnt the small green pieces that were unhappy. And so the problem remained; lots of people were mean and most of them were miserable even the ones with the digital watches.

Many were increasingly of the opinion that they’d made a big mistake in coming down from the tress in the first place. And some said that even the trees had been a bad move, that that no one should ever have left the oceans.”

My take:
How nice it would have been to swim around as a fish carelessly to be eaten by a shark one day minus the worries of thinking and waiting for that one day :-). Have you heard of a fish that died of a heart attack because it was worried that one day a shark will come and eat it. I though have heard of a lot of homo-sapiens that die at 40 worrying all their lives on how to create the retirement fund to be used at 60. Dont you want to be a fish ?