MODULES: Fuel Tank - #00049
There's not really much to say about fuel tanks :-)
Your ship is factory equipped with the largest core module fuel tank available. It's usually good for 80-120 ly on multi role ships and 40-80 ly on combat ships - with a huge spread depending on module quality and other factors.
Equipping a smaller tank can be useful if you're using your ship only locally, but be advised that some ship's standard fuel tanks are quite small. Equipping an even smaller tank on a Fer de Lance for example will open up the option of running dry after a quite short time.
In the opposite 'direction' you can add optional fuel tanks into your optional module slots. Although this does expand your ship's range, it adds a lot of weight, too. Go for an (optional) fuel scoop instead, no weight and unlimited fuel reserves as long as you make it a habit to refuel at every scoopable main star.