Yes, that is the English language for you, it really needs to be revamped. Do we really need the same word meaning up to 5 different things depending on the situation?
In a choir, there's generally four different ranges of vocals. In order of highest pitch to lowest pitch, they are Soprano, Alto, Tenor, and Bass (or basso). This mob is following the pattern of 'soprano', 'alto', and 'tenor' mobs in the zone, and not with the fish.
I'm just suprised that the entry for 'a soprano' wasn't filled with TV Mobster references.