The cheese is in the castle dungeon. Recover it and feed the mouse in the Maid's room.
To get into the dungeon :
After you get the cheese you put it in the princesses dressing room and capture the mouse to feed it to the owl.
In the Maid's room (castle first floor left), feed the cheese to the robot mouse.
the mouse is in the princesses room in the hole in her wall but you have to get the cheese to get him/her.
To catch the mechanical mouse, in the Princess's Maid's room (castle first floor left).
In the Maid's room (castle first floor left) you will find a mechanical mouse.
you put it in the room with the mouse in the astro knights castle and the mouse will eat it
The only place is in the castle dungeon, below the library. (see related question)
Use the cheese from the dungeon (under the library in the castle). (*To get to the dungeon, see the related question.)
you need the hovercraft,mouse,moldy cheese, owl,green glowy thing,coordinates, and find the broken paceship.
Find the old cheese. . Give the cheese to the mouse and give the mouse to the owl.
get the moldy cheese from the basement of the castle and lay it out in the bed room
There is no fish. You have to get the mouse from the madian's room and feed it to Merlin. You lure the mouse with the moldy cheese you get from the dungon.