Unlike in England, Wales or Ireland; in Scotland you do not need to have a fishing licence from the Government.
The only exception to this is the Border Esk which flows into England and is therefore considered to be an English river for legal purposes, hence you need a current rod licence for it. The opposite is true on the Tweed, where the English part is considered to be Scottish for legal purposes, so even there you do not need a licence.
However when fly fishing in Scotland it can be a bit of a daunting experience but the main points to be aware of are as follows:
Permission to fish:
Please be sure to get the correct permissions before you go fishing, as otherwise you may be committing an offence. For salmon & sea trout, it is a criminal offence (the state can prosecute you) to fish without written permission from the owner of the fishing rights, or his agent.
For trout, it is a criminal offence to fish without permission where there is a Protection order in place, or where a loch is in single ownership. In all other cases, it is still a civil offence (the owner can prosecute you).
For other types of freshwater fishing it is a criminal offence to fish without permission on a single ownership loch and a civil offence in all other cases.
For more details see the Salmon and Freshwater Fisheries (Consolidation) (Scotland) Act 2003.
For fishing in the sea, by boat or from the shore, no permission is required.
Salmon and trout fishing on rivers are subject to a close season during which it is illegal to fish. These vary from river to river.
The earliest Salmon River to open is the Helmsdale on January 11th and the latest to close is the Tweed on 30th November. However most salmon rivers open on 1st February and close sometime in October.
River trout fishing dates are 15th March to 6th October but many fisheries do not let outside the period from 1st April to 30th September.
There is no legal close season for rainbow trout, grayling, coarse or sea fishing, although some fisheries do not operate in the winter.
For salmon or sea trout fishing in Scotland, Sunday is a closed time and it is illegal to fish then. For other fishing, it is not illegal and most commercial Stillwater fisheries operate on Sundays, although many river fisheries do not.
In Scotland it has recently been made a criminal offence to sell a salmon or sea trout, so always put your fish back unless you intend to eat it yourself and then only do so if the conservation rules of the river allow it; which some don't! There are no legal restrictions on keeping other fish types although many fisheries will impose limits.
The requirements vary according to species being fished for and the area of Scotland in which you are fishing. Fishing is legally restricted to rod and line only, but many rivers have extra legal restrictions, such as the Tweed where you can only fish by fly for much of the season.
Other rivers have conservation codes which mean that fishery owners will ban the use of spinners, prawns, worms etc for all or part of the season