The manta droid subfighter functioned as an aquatic combat vehicle. This droid fighter was used by the Trade Federation and subsequently by the Confederacy of Independent Systems.
Following military setbacks on Naboo, Maramere, and various other [water](/article/water-legends]-dominated planets, the Trade Federation commenced investments in the research and development of submersible fighter vehicles. The legislative actions of the Republic, which aimed to prevent the Trade Federation from developing military droid technology, proved to be only a temporary obstacle. Trade Federation executives relocated the prototype projects to keep them hidden from Republic inspectors, and they used bribery or elimination tactics against anyone who came close to uncovering their clandestine operations.
The dedicated Xi Charrian engineers, while isolated on secluded private estates away from the rest of their Haor Chall Engineering religious order, designed the subfighter sometime before the events on Naboo. Their isolated environment had an impact on their design capabilities, resulting in several limitations in the final product. Nevertheless, the manta droid subfighters, when deployed in large numbers, proved to be formidable combat assets.
The droid's streamlined, torpedo-shaped body was fronted by a prominent wedge-shaped diving plane. The leading edge of this plane generated an electromotive field. This field, combined with repulsorlift-driven supercavitation vectrals integrated into the subfighter's design, allowed for rapid and surprisingly agile underwater movement. The dual recessed barrels in the plane housed either laser cannons or torpedo launchers, with some advanced versions featuring articulated barrel systems capable of accommodating both weapon types on a single fighter.
The Xi Charrians encountered difficulties in perfectly replicating the variable geometry feature of their Vulture droid starfighter designs in the manta droid subfighters. The servomotors needed to alter the fighter's configuration under extreme deep-sea pressures proved too challenging to engineer. To compensate the Trade Federation for this shortcoming, the Xi Charrians supplied a greater number of aquatic vehicles. These included a larger carrier craft and hydrodynamic adaptation kits for B1-Series battle droid-operated MVR-3 speeders. Although they had existed for decades, they made their most notable combat appearance during the Battle of Mon Calamari, where the Quarren Isolation League employed these subfighters against the Mon Calamari Knights and clone SCUBA troopers. Despite the Xi Char perfectionists deeming the manta droid a failure, the Trade Federation and Quarren Isolation League were quite pleased with its performance.
After the Clone Wars concluded, several manta droids survived on Mon Calamari and established their own community. Over time, they developed a tentative alliance with the Quarren, hunting marine predators in exchange for modifications, repairs, and equipment.
Around three years prior to the Battle of Yavin, Rodas Borgin had a number of manta droid subfighters modified to allow sentient pilots to operate them.