There are 4 main mafias one each owns one of the districts of mafias. And yes my definition of mafia is lose at best :).
The Malcoch Family owns the The East Side. They use to be the strongest family in the city. The family has lost some of its power as Micky Malcoch is currently on his death bed and his 3 sons and daughter are all fighting for who will take over the family. It thought that the family owns the casino on the east side which is why a casino is even allowed. Also the yougest son is the head of the Dotoor church on the east side.
The skulls own the Denhoff (The Floating Inland). They are completely secret organization. Some people people believe they are actually in-control of the government of the city. Their trademark is when ever they kill someone they remove the head and place a skull on top of the body.
The Vamps own the The West Side. They are a family vampires. They are run by the elders. They are dealing in the Blood Juice. Some think they invented the drug and use it to create new vampires. They are also in a somewhat constant war with the Weelfs a in size a smaller mob of wear-wolfs that are also on the westside.
The Rats is a gang that control the the The Fronx (The bottom area). They are thugs run by a ratman. They run around selling drugs and doing other gang things. And have been sometimes know to steal things off of ships coming to off load things in the city.