Antimatter is often depicted as the ultimate rocket fuel, while it promises great performance it has many limitations, this thread focuses mainly on the pion antimatter rocket and some variations of itself and how it works as a fuel for (fast) relativistic interstellar rockets. Pion rockets work by annihilating hydrogen and antihydrogen, quarks and antiquarks annihilate and create pions, which are either neutral or charged. The charged pions can be redirected out of the magnetic nozzle for thrust, energy is lost due to neutral pions and inefficiencies.