An assembly of fuel tank and bubbler system comprises a fuel tank defining a storage volume adapted to receive fuel therein. The fuel tank comprises at least one fuel inlet, at least one fuel outlet, and at least one gas inlet adapted to be connected to an inert gas source to feed inert gas to fill an ullage in the storage volume. A bubbler system has at least one pipe extending into the fuel tank and adapted to be immersed into the fuel of the fuel tank. The pipe has a porous structure. The pipe is adapted to be connected to an inert gas source to inject inert gas via the porous structure into the fuel of the fuel tank. A method for treating fuel in a fuel tank is also provided.