Fish and other seafood are a major component of New Zealanders’ diet; the 2018/2019 and 2019/2020 New Zealand Health Survey found that nearly three quarters of New Zealanders eat seafood at least once a week(1). Environmental and ethical factors influence New Zealand consumers’ purchase of seafood and consumers prefer to get their information about seafood at the point of purchase(2). However, environmental claims are not regulated under the Australia New Zealand Food Standards Code, unlike health and nutrition claims. Some seafood products are certified by programmes (e.g. Best Aquaculture Practice (BAP)), ensuring the seafood was sourced according to specific criteria related to environmental management, but other products carry self-declared environmental claims that have not been independently verified. This study aimed to describe labelling practices, including environmental claims, on fish and seafood packaged products sold in major New Zealand supermarkets and available in the 2022 Nutritrack database. Nutritrack is an annual survey conducted by trained fieldworkers who take photographs of all packaged food and beverage products displaying a nutrition information panel (NIP) from 4 major supermarkets in New Zealand. Information from the photographs, including the NIP and the ingredients list is entered into the Nutritrack database. For this study, data (including fish species, harvest location, processing country, fishing method, environmental certifications and self-declared environmental claims) were extracted from the archived photographs of all sides of the packaged fish and seafood products in the 2022 Nutritrack database. Self-declared environmental claims were assessed against the ISO 14021 standard for “Environmental labels and declarations — Self-declared environmental claims (Type II environmental labelling)” on specific criteria that were relevant for seafood products, including if the self-declared claim mentioned the word “sustainable” (as this term is difficult to substantiate and should be avoided); was vague and non-specific; or overstated the benefits (to imply multiple benefits from a single environmental change). There were 369 fish and seafood products included in this study. Eighty-eight products (23.8%) displayed a certification; the Marine Stewardship Council’s certification (MSC) for wild fish was the most common and was featured by 72 products (19.5%). One hundred and fifty-two products (41.2%) displayed at least one self-declared claim. Thirty-three distinct self-declared environmental claims were identified, 16 (48.5%) of which breached the ISO 14021 standard for environmental declarations because they used the term “sustainable” and 26 (78.8%) of which breached the ISO 14021 standard because they were vague. This analysis suggests that stricter regulation is needed for self-declared environmental claims on fish and other seafood products available for purchase in New Zealand, to prevent greenwashing and to provide consumers transparent, accurate and substantiated information.