Owen Wilson -- New Son's Name Is Fishy

Owen Wilson's brand new baby boy will probably be a good swimmer ... because his name is Finn.

Finn Lindqvist Wilson was born at Cedars Sinai in L.A. on January 30th, 2014 to Owen's 42-year-old personal trainer Caroline Lindqvist ... who's currently married to another man.

Lindqvist is reportedly going through a divorce but apparently decided to get over her old man by getting under a new one.

Finn is Owen's second son. Owen and his ex-GF Jade Duell had Robert Ford Wilson in 2011.