Though, in general, it is not a criminal offence to fish for or take trout and other freshwater fish in Scotland, this does not imply that there is a free right to fish anywhere. The rights of riparian owners (who own the fishing rights) are protected by principles of civil law and permission should always be sought before fishing. No one, even if they are lawfully on the bank of a river or loch under a right of access, has an implied right to fish there. Fishing is only available to the owner of a fishery or with their written permission. Unlike in England and Wales, no national rod licence is required to fish in Scotland.
Please see section 11 of the 2003 Act which states "Any person who without legal right, or without permission from a person having such right, fishes in a proper stank or loch shall be guilty of an offence, and liable on summary conviction to a fine not exceeding level 1 on the standard scale."