A roughly spherical shaped object in space (like earth) transforms into a more egg-shaped spheroid with two buldges (high tides) due to differences in graviational influence. One on the side of the attractor (i.e. a moon) and the other on the opposite side.
Gravitational force will decrease exponential to the distance from the objects barycenter. Therefore, liquids on the side of the moon will accelerate quicker towards the moon while liquids on the opposite site will 'fall behind'.
The answer to your question is different depending on the location of the fuel tank.
On earth, the fuel tank is mechanically connected to earth and therefore, the fuel will generally experience the same behaviour than water in oceans. However, it is limited in its movement by the sidewalls of the tank. If the tank is in a high tide area, the fuels volume will increase and the pressure will decrease.
In space, the entire crafts trajectory will always be partially influenced by the moon (assuming you're between VLEO and HEO for the sake of simplicity). If you want to read more about that, search for 'n body problem'. The fuel inside the tank experiences tidal forces as well, depending on the location of the fuel relative to the barycenter of the overall craft/fuel tank. They will (if not influenced by stronger forces) 'fall behind' or get ahead relative to the moon.
Edit: Tidal forces on a fluid increase, as the distance of a liquid from the barycenter increases. This is due to the difference in gravitational influence from the external attractor. Therefore, tidal forces in fuel tanks in space are probably diminishable (If someone bothers to do the math, please go ahead).