Korbro I've discussed before; Montrose, though reportedly a family-owned business for some 60 years, has left little trace other than this sign. Korchin, whose sign is the most faded, has the most celebrated legacy. The successor business, Marshall Smoked Fish, was acquired by an out-of-state company in 2003; it's unclear how much of its fish, if any, is still smoked in Brooklyn.
Korbro Salad Oil, Korchin Bros., Montrose Smoked Fish
Surviving signage, 71 Montrose Ave. (Lorimer-Leonard Sts.), Willamsburg, Brooklyn