The Dink Network

The yellow snapper trout sometimes shows up in the upper right corner of the Land of Reverence, and theoretically, you can get it by throwing things at it. However, I'm not sure you can get it anymore in the newest version (what you throw at it may simply fail to reach it).
The man who asks for it doesn't actually "teach" you anything, he's part of a sidequest that would have allowed you to get a happier "good" ending in this chapter. However, SimonK never completed this quest, possibly in part due to the lack of map space.

For those who are curious, this is what happens when you bring him the yellow snapper trout. Major spoilers ahead, obviously.

Fake wizard : Have you got me a yellow snapper trout yet?
Dink : Yeah, here it is...
Fake wizard : Excellent... Excellent... time to make some buttered trout, with parsley!
Dink : Aren't you forgetting something?
Fake wizard : What? Oh, yes. You're right. I don't have any butter. Have you got any butter on you?
Dink : NO! Now look here, I brought you your trout, show me your magic!
Fake wizard : Don't yell at me!, or I'll turn you into a... a fish!
Dink : You couldn't turn over a page in a book! I don't think you know any magic!
Fake wizard : Of course I don't know any magic, but I can sure cook fish!
Dink : No magic?!? Go back to playing leap stone. This has just be a waste of time!
Fake wizard : Not for me! Yum, it's fish for dinner tonight!

If you learned enough about the Satin Knights and their connection to Mary, you would then get an option to "beat this lying b*stard within an inch of his life". Then this would happen :

Dink : I don't take kindly to being cheated!
Fake wizard : I DON'T care.
Dink : I'm waiting...
*Dink then proceeds to hit the fake wizard. A lot.*
Fake wizard : Oww... No... stop... I want my fish battered, not me!! ...enough...
Dink : Listen, I will not stop until you tell me something! And no more lies!!
Fake wizard : OK, OK... I will confess... I betrayed Prince Richard...
Dink : What?
Fake wizard : I... I used to work for the Satin Knights... And I betrayed the Prince for ... Oh... I forget... lots of gold, I think... But that beating you gave me has given me a headache...
Dink : So what happened to the Prince?
Fake wizard : Oh, he's probably gone insane by now... he's been locked away for so long. I used to visit him and eat fish to tease him. Ah those were the days... A nice piece of sizzling fish, and the sounds of a Prince raving.
Dink : I take it you didn't share your fish.
Fake wizard : No, just its smell. I can still hear his lips smacking beneath my feet.
Dink : Beneath your feet?
Fake wizard : Yeah, he was underground. Probably still is, if he hasn't run out of bugs to eat. I became his last friend, as it were... hmmmm... He told me lots of things... even of his lover.
Dink : The woman who rejected him?
Fake wizard : Yep. Funny story that... I even know where she is now.
Dink : The Forest of Wickedness...
Fake wizard : Hey, how did you know about Mary?
Dink : Did you tell him about his daughter?
Fake wizard : The kid? yeah... I never knew what gnashing of teeth was... until I told him.
Dink : So where was his prison?
Fake wizard : Not far from the Castle... that's the funniest thing... But you can't get there now... The Church has removed the steps... Just left the blue rock I used to sit on. Oooo, I hurt all over. I gotta lie down....
Dink : Blue rock near the Castle, you say...
Fake wizard : Yeah... I'm sorry... And thanks for the fish.

Then you would have been able to trigger this conversation with Mary :

Mary : Have you got nothing better to do?
Dink : I wonder why you live out here.
Mary : None of your business.
Dink : Where's your daughter's father?
Mary : None of your business, I said!
Dink : I think you're the vessel that I'm looking for. And if your daughter cries the jewel will appear.
Mary : This is utter nonsense!
Dink : I think if her father came back.... Then little Josephine would cry like you've never heard.
Mary : Ha, you don't know my daughter. Begone with you!
Dink : Oh... I'll go, and find ... Little Richard!
Mary : Get out of my house! Richard is dead!!

At this point, you would have been able to enter the secret place near the castle and presumably rescue Richard.