Most fish live underwater, which is a terrible place to have sex
because virtually anywhere you lie down there will be stinging crabs
and large quantities of little fish staring at you with buggy little
eyes. So generally when two fish want to have sex, they swim around
and around for hours, looking for someplace to go, until finally the
female gets really tired and has a terrible headache, and she just
dumps her eggs right on the sand and swims away. Then the male, driven
by some timeless, noble instinct for survival, eats the eggs. So the
truth is that fish don't reproduce at all, but there are so many of
them that it doesn't make any difference.
-- Dave Barry, "Sex and the Single Amoeba: What Every
Teen Should Know"