For better efficiency, get a witch doctor alchemist.
It has a recipe that makes 5 oil from 1 bark and ichor.
Bark is not too hard to get 1000 of, and fish cook into ichor way faster than press into oil.
Plus now you can get 5 oil out of one blue fish, and also don’t have to decide press for oil or cook for ichor. Just make them all ichor, and craft into oil as needed.
This is for the blue fish only. I put the medium and bigger fish in press just to get something out of them.
Plus the press only goes one speed, you can speed cooking up with named cook.
Plus all the extra fish can be used on thrall wheels. so no waste, and more uses out of the one blue fish.