Fish was the basic element for the preparation of "garum". Apicius also explained how to make it more fragrant
The Garum (or Liquamen), as is well known, it was the favorite sauce of the ancient Romans, who put it a little everywhere (https://www.pilloledistoria.it/1787/storia-antica/garum-liquamen-salsa-preferita-dai-romani).
Although the flavor should not have been bad given the wide use made of it, deriving from the maceration and subsequent salting of some types of fish, the scent of garum could not be the best, so much so that it is described as strongly acrid and pungent.
Apicius however, the great cook who lived in the 1st century AD did not fail to provide valuable suggestions in this regard.
Also the garum it could become less smelly, just take a few little strategies.
In this regard the chef suggested emptying the jar in which the fish sauce was contained, smoking it with cypress and bay leaf and finally putting the sauce back into it.
If, on the other hand, you wanted to increase its sweetness and remove some degree of acidity, you could add a little honey, another omnipresent food in the cuisine of Ancient Rome.