According to torontofilm.net:
Casting is looking for "...5 different groups of otherworldly creatures..." :
Goth/punk/fetish types, they can have been in the bar scene in the first movie 18-35 yrs, any ethnicity.
Lumberjack/biker types, big, rough, hairy, 18-45 yrs, any ethnicity.
Exotic looking/Asian/Persian/interesting looking MEN ONLY any ethnicity EXCEPT for Caucasian. The following actor Godfrey Gao plays 'Magnus Bane' the 'head' warlock. This should give you an idea of what they're looking for 18-45 yrs.
Pale, skinny, fragile with wide set eyes. Lily Cole is playing the 'Queen of the Faeries'. Men and Women 18-40 yrs, any ethnicity.
Young, fit performers (gymnasts and swimmers not bodybuilders). Most of the lead actors are 'shadowhunters' 18-35 yrs, any ethnicity.
Shadowhunters, who is excited about this?! Please comment below or tweet us @TMI_Institute!