What does よし！久しぶりに魚にしようっと！ mean?

Question

So I am reading Dragon Ball in Japanese and I got stuck with this sentence. Goku is looking for food and looks down at a river and says:

よし！久しぶりに魚にしようっと！

which I think means something like

Nice! It's been a while since the last time I ate fish!

So I can understand it by context but I would like somebody to break it down for me and explain to me the use of the two に and especially しようっと. Thank you very much!

Answer 1

• よし in this context is closer to "Okay" or "Alright" said when you've decided something. It's defined as 決意する時に発する声 in this dictionary entry.
• 久しぶり is a noun that works as a no-adjective (sometimes also as a na-adjective). There is no single-word equivalent in English. This に after 久しぶり is used to turn a na-/no-adjective into an adverb.

  • 久しぶりの休暇　first vacation in a long time
  • 久しぶりに走る　to run for the first time in a while

  (Note that 休暇 is a noun and 走る is a verb.)

• ～にする is a very common set phrase which has several meanings. In this case, it means "to decide on ～ (from multiple options)" or "to choose".
• しよう is the volitional form of する.
• For っと, see What does volitional form + っと mean?