Staff from the competition watchdog, police and other government departments on Sunday visited the Aberdeen Wholesale Fish Market to investigate reports of price-fixing.
The Competition Commission said it was acting on a complaint that wholesalers engaged in price-fixing, which contravenes the First Conduct Rule under the Competition Ordinance.
It spoke to staff at 30 wholesalers and appealed to anyone with information on the case to get in touch. The commission says it will protect the identity of informants and consider information passed on anonymously; it also urged anyone involved in cartel conduct to approach it to seek leniency.
As well as police officers from the organised crime and triad bureau, staff from the Food and Environmental Hygiene Department and the Agriculture, Fisheries and Conservation Department were also involved in the operation.
The commission reminded the public that anti-competitive conduct might contravene not only the Ordinance, but also different areas of law, including criminal offences.