First i bought the finder.

The Timer is for 4 Hours Real Life time.
Then i got myself on the ship and i used the finder.
First i got a message that ther was nothing to find.
But after just a little bit the finder saw something.

I keep following the directions it pulls me too.

Seems like the right spot to start fishing!
Then i pulled up a Yellowtail Barracuda.
And another.. and another... and another....

I kept checking my finder while fishing untill it said the shool was north of me.
The range of the finder is pretty big but you can have spots where the finder see nothing. Then just keep moving the ship.
But I had to test to see if it would find other fish,so i moved my ship to tokuno.
and sure did find a school of Giant Koi!

4 hours is plenty to find those rare fish. I sure could use this finder to get me some Blue Marlins.
I ran a bit trough Underworld and the Abyss. But i did not find shools there. I'm not suprised by that.
But So far Tokuno,Ilshenar,Trammel and Felucca work fine with the finder.
The one in Ilshenar is a bit strange,I can't place a boat there but it showed me a school in the middle of the Lake of Fire.
Great Barracuda in Felucca.

Fairy Salmon In Ter Mur.

Always seem to pull up 4 of the big fish before the school moves.
Only found school of fish that can be made into pies.
Not used any baits for anything.
Might be that with bait you can get more then 4 big magical fish at one spot...
The Fish Finder Works in Dungeon Doom!
And the Labyrinth...
Gravewater Lake in Malas...
Twisted Weald...
Dungeon Shame...
Dungeon Destard...
So everywhere where you can find magical fish that can be made into pies.
Tested Fire Fish with Fish Finder in Dungeon Shame with Bait.
Still can get just 4 fish with the bait before the school moves.

But i pulled the 4 up faster then without the bait.