Well, we knew this day was coming and yet it found us unprepared.
Going by the thermal readings from the Gravhund that they ran down (500 ton fighter with a gen1 grav sensor, a jump drive, a high efficiency engine and nothing else)- x8 18,200 tonners, x3 36,400 tonners, x3 54,600 tonners, x1 active sensor contact of indeterminate tonnage- and that's just the laser boats. Anything else that is out there would not have been seen. There is a sensor outpost in Sirius, Alpha Centauri is empty, and once in Alpha Centauri they either follow the civilian traffic to the only relevant source of Gallicite for an empire of 12 planets (itself with a population in the hundreds of millions on the theory that in the extreme long term terraforming and manned mines is a more efficient way of mining a few million tons of gallicite than automated mines), or Sol.
I won't "officially" know they even exist unless somebody trips over the wreck of the Gravhund (unlikely, and it won't be overdue for years), or somebody enters Sirius after they do (also unlikely, total backwater). EZ Aquarii doesn't stand a chance. Sol might, but it would be ugly- shipbuilding capped at 30,000 ton battleships with a Particle Beam/Missile mix, and the missile size has been declining over the generations, there could be anywhere between 0 and 24 of them available at the moment of crisis (the fleet spends most of its time camping wormholes and responding to locust people. The entire mobile reserve fleet is garrisoning a distant NPC conquest). PDCs are a joke, the 120 odd Torpedo FACs could at least launch a salvo of modern missiles but only 60 of them are concentrated.
The one bright spot is there is so much civilian stuff in space that they may actually shoot their magazines dry before they get around to testing our planetary anti-missile capability, which may be insufficient if the missile boat element is equivalent to or exceeds the laser boat element.
