ΔE 11.9, fair: the same colour family, but not a straight swap. Ultramarine Blue is a little 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 12). Ultramarine Blue is a little darker, more saturated than The Fang.
The same difference applies the other way round: The Fang is a little 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 Ultramarine Blue on the colour wheel
All matches: The Fang equivalents · Ultramarine Blue equivalents