"The shark's food is the fish."
Translation:Il cibo dello squalo è il pesce.
That's true for sheep, but not for fishes: there aren't many instances in one's life when you'd want to use the word, but it definitely exists: http://www.collinsdictionary.com/dictionary/english/fishes. Another word that many ignore is "chickens", the plural form that should be used when speaking about live fowls.
Where are you from? Chickens is a normal word to me. Sometimes chooks. Never fowls.
Oxford says that fish is plural of fish here: http://oald8.oxfordlearnersdictionaries.com/dictionary/fish_1
If this is so, then I pesci should be excepted. The sentence could mean "the single fish", "the many fish", or "the range of different types of fish (fishes, if you prefer)".
Because Italian words (or pair of words) can never have 3 consonants in a row, except "str" and few other cases. In "dell squalo", "ll sq" would even be 4 of them!
It's simply impossible to be pronounced in proper italian and it represents what they call "a fiscal code", as a joke :)