There is a little cove, called Ballybrassil, on the southern shore of Tír na nÓg. For as long as folklore stretches back it has been the dwelling-place of Mac Carell, a fish composed 95% of brain.
Such is the awe (or perhaps distain) in which lesser fish hold him that if caught in a tight spot, they will leave the water and hide in the undergrowth rather than be in his presence.
He is said to contain the memory and the wisdom of the ages within his cranium.
Many eminent scientists have attempted to communicate with Mac Carell but have been spurned by him. Even the dolphins have failed to gain his respect.
He should not be confused with the "Breadán Feasa" (The Salmon of Knowledge), whose flesh imparted wisdom to whosoever ate it.
Finn Mac Cumhail became a wise thumb-sucker after burning his thumb on the flesh of a Breadán Feasa as it was being cooked by Finegas. Before the event he was reputedly "as thick as two short planks".
Anyone wishing to emulate Finn's transformation by nibbling at Mac Carell should be aware of the following.
How to capture the fish and access his store of knowledge?
Suggestions are welcome in the Message Board.