Salmon indeed! PAH!

A lot of wells once had sacred trout. They were orcular and gathered their wisdom from the nuts that fell into the well:

The sacred trout of wisdom represented Ban Naomha, the Irish fish goddess.

http://www.irelandforvisitors.com/articles/holy_wells.htm

http://www.sacred-texts.com/neu/celt/ali/ali199.htm

The 'salmon of wisdom' is splitter! He was basically a scribe's error from the 7th century, consequently appearing in such places as the story of Finn McCool's prophetic thumb.

http://www.howardism.org/thoughts/000251.html