Only 1 fresh fish is needed.

According to the EU BDO version the correct in-put is :

(Copy Paste from my previous written post on same subject)

……the "new" recipe requires/ new ingredients are as follows :

1 Mudskipper* + 1 Saurel* + 3 Onions + 2 Cheese + 2 Dressing

NB ! = You have to use 2 different kind of fish in the recipe (e.g. – fill 2 slots with 2 different fish in the cooking window (or it will not succeed !))

* = You can substitute dried fish or a different fish ingredient, of the same tier, for the fresh fish ingredient.
For example, you can substitute 2 'Dried Mudskipper' for the 1 (fresh) 'Mudskipper' (or vice versa).

100% success rate with this recipe at master 2, would be nice if someone lower can confirm.
1 Dried Sea Eel (blue quality)
1 High-Quality Onion (sub for 3 normal)
2 Dressing
2 Cheese

Image for proof

Used two dried fish of different types with 100% success rate. @ Skilled 9