How do I take care of the cat Manannon?

Hint 1 of 6:

What do most cats like?

Hint 2 of 6:

Fish.  You found a fish on the shore, didn't you?

Hint 3 of 6:

Give the fish to the cat.

Hint 4 of 6:

But he'll get away if you can't trap him.

Hint 5 of 6:

Did you attack the blue beast yet?