The people you see on the cover are all famous people that died of
drugs/alcohol. Fish was influenced by most of these people.

On the front from left to right:

        Robert Burns, Dylan Thomas, Truman Capote and Lenny Bruce

On the back from left to right:

        John Lennon, James Dean and Jack Kerouac

Here's the story behind those people:

James Dean died in a car crash, but was probably drunk when it happened.
He was an alcoholic and also used drugs. Jack Kerouac died of alcohol
poisoning, but also used drugs. Dylan Thomas also died of alcohol
poisoning. Truman Capote died of a combination of alcohol, drugs, and
whatever pills (probably suicide). Robert Burns died of alcohol poisoning,
Lenny Bruce died of an overdoses heroine... John Lennon does not exactly
fit in this (pleasant) group of people, he was not an alcoholic, nor a
heavy drugs user. But, as someone put it: he probably died of an overdose
of fame...