Fish Warden is a new addon that many fisherman may find very useful. It has configurable filters to determine which fish you want to keep - which Fish Warden will auto loot.
The main advantage is the speed of having auto loot turned on, with the added convenience of not having your bags fill with useless junk.
The achievement filters are intelligent enough to only loot the fish you still need - i.e. it won't auto loot the same Dalaran coin twice.
The quality filters allow for a 'safety threshold' so that all fish of the selected qualities are always auto looted.
There are also filters for quest items, fish feast, and the fish required for the STV and Kalu'ak fishing contests.
Finally there is a "Custom" filter which allows you to type additional fish you also want to auto loot. You type the list either by item id number, or by item name (partial names are acceptable).
Normally any fish which are not filtered for auto loot are left in the Loot Window for you to decide whether you want to manually loot or discard. However, there is an option to "Automatically release unwanted fish." This option will automatically close the loot window ONLY after Fish Warden is sure it looted all the filtered fish. Also with this option, after every catch a brief summary of the kept and released fish is added to the chat window.