Duckfish is a facial expression people use when taking a selfie. It's like the duck face/lips gone wrong. The Duckfish is combination of duck and fish lips.
Did you see (insert name) picture on snap chat she was doing a Duckfish facial expression, so gross.
The act of using a social media account, with a duckface userpic, to send a friend request to a stranger, usually for scamming purposes.
'I don't have any friends in common with that woman on Facebook, but she'd be pretty hot... if it wasn't for that stupid duckface!'
Careful, mate! She's probably duckfishing!