Improving health and sustainability outcomes in WEIRD (Western, Educated, Industrial, Rich, Democratic) nations necessitates a reduction in red meat consumption. Seafood is often overlooked in achieving this goal. However, simply consuming more of familiar fish species places high stress on production of these species. For this reason, diversification of seafood consumption is also critical. Here the motives for seafood consumption (frequency and diversity) are investigated across two studies by adapting the 4Ns survey to the seafood category. This 16-item survey measures four factors underpinning meat consumption: namely that it is 'Natural', 'Necessary', 'Normal' and 'Nice'. Swedish consumers' hedonic and sensory expectations of two herring concepts (traditional pickled contra novel minced and presented as a burger) are also evaluated in relation to the 4Ns. Study 1 (N = 304) revealed that the seafood 4Ns scale had a similar underlying structure to that of meat and had good test-retest reliability. Study 2 (N = 514) showed that consumers expected to like the pickled herring (associated with being 'seasoned', 'salty', 'sweet', 'firm', 'juicy', 'chewy', and 'slimy') more than the minced herring (associated with being 'mushy', 'fishy', 'grainy', 'dry' and having 'small bones'), and that 'Nice' scores affected expectations of both herring concepts. Food neophobia correlated inversely with seafood consumption frequency, expected liking, the 'Nice' subscale, and food agency. Critically, in both studies, enjoyment of seafood (higher 'Nice' scores) predicted more frequent and diverse seafood consumption, whilst agreeing that seafood is 'Necessary' for health predicted only consumption frequency, not diversity. Communicating the positive sensory attributes of seafood and developing novel product concepts in ways that disconfirm sceptical consumers' negative sensory expectations may increase acceptance of both familiar and unfamiliar seafood concepts.