Waste from fish farms (such as faeces and chemicals) can collect on the seabed under fish cages.
To make sure this does not cause too much damage to the environment, you are legally required to apply for a Controlled Activities Regulations (CAR) licence, which can be withdrawn if you fail to meet water control standards. These standards are enforced by the Scottish Environment Protection Agency (SEPA), which sets site-specific limits on the amount of fish held and the amount of medicines and chemicals that can be used.
You do not need a CAR licence if you're running a shellfish farm: it only applies to fin fish farms.
Before applying for a CAR licence you should first contact SEPA to discuss your proposal and obtain advice on any potential difficulties. SEPA also has a guide to the pre-application process.
When you are ready to apply for a CAR licence, the SEPA website provides a Fish Farm Manual which takes you through the process and provides example forms. SEPA also provides information on modelling and technical guidance to support operators.
Details of CAR consultations are avaliable on the SEPA web pages.
For more information you can contact SEPA using the details on its website.