ΔE 13.8, fair: the same colour family, but not a straight swap. Prussian Blue is noticeably darker, more saturated than The Fang.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 14). Prussian Blue is noticeably darker, more saturated than The Fang.
The same difference applies the other way round: The Fang is noticeably lighter, more muted.
ΔE is the colour difference between our two swatch estimates: under about 6 is close, over about 15 is loose. Real paints also differ in finish, coverage and how they thin, so test before you commit.
See The Fang on the colour wheel See Prussian Blue on the colour wheel
All matches: The Fang equivalents · Prussian Blue equivalents