Shopkeeper challenge: Catch a Gold Rank Mountain Whitefish (stuck)

[Yuccasu]

I am playing The Angler for a few days only, but now I am stuck on this mission. I got tons of rainbow trouts, some silver mountain whitefish but not a gold one. I tried float fishing with dough and eggs, hooksize between 6 and 8. Spin fishing with spinner and spoons size 6/7. Different location and time throughout the day and night. What do I miss?

[Portwills]

Spinner size 7 should do it. Are you fishing around the location they sent you? Mountain Whitefish should be around the bottom of the water, night time favorably but they bite in the day too. I never noticed much of a difference between day time and night time. Sometimes they are also right on the coast.

[Sciurus]

hook 7 with eggs should work fine. Make sure you on the right lake i always catch whitefish near shore watch for bubbles or jumps then shortcast you can easy spot them near shore also.

[Yuccasu]

Thank you for your comments. I fished another day with the gear you suggested, tried it at different times of the day, went back and forth the shore, turned the challenge off and on .... and finally after some 20 Silver Mountain Whitefish and dozens of Rainbow Trout have hooked a Gold Mountain Whitefish.