RE:Fishing Ireland? A must see post...
as regards the basic legislation this is uniform across the country, but there are some local bye-laws such for instance fly only for sea trout on some rivers, or a later opening of the season.
As regards stopping to fish a nice looking water the best advice is to travel with a copy of Peter o'Reilly's Rivers of Ireland (and a copy of Loughs of Ireland too) and a good map. These books list just about every body of water with a fish worth catching. And they give all the important information such as local bye laws, opening times, cost(if any), who owns it(club or association etc), who to approach for permission and their contact details.
I use both books as a bibles for getting around waters, they even suggest best times of year and patterns to try.
So sum up, if fishing for sea trout or salmon you need a license, if for brown trout you don't. Most rivers are controlled in some way by a club so check if you need to ask permission to fish, most lakes on the otherhand are free and full of superb wild fish.
There is a new tagging system for salmon and sea trout over 40cm, but I think in most waters release of sea trout is still promoted.
If you would like more detailed details get in touch either here or directly,