If it were me, I would only use salt with the ingredient 99.9% NaCl.
The reason being, Sodium Ferrocyanide can release free cyanide (toxic) if it comes in contact with acids.
There are always some acids in aquarium water (uric acid, tannic acid, etc)
Although as an anti caking agent it could be only a trace, the % concentration is not listed in the pic, I might nort be worried if the concentration listed was 0.02% or 0.01% or something on that order..