Hive Fleet Acheri is a splinter Hive Fleet that recently emerged from the world of Kerodan after losing its connection with Hive Fleet Moloch. Thought destroyed, the Imperial forces that dealt with Moloch moved on to more pressing matters that needed to be dealt with the end of a boltgun. Not knowing that a more deadly foe is slowly building up its force.
It was again discovered in the closing years of the 41st millennium when the splinter hive fleet assaulted several sectors. Engaging in multiple conflicts that so far seem to be a stalemate. Only time will tell if the efforts of the Hive Fleet would all for nothing and will be cast aside into nothingness.
Originally an infestation long forgotten after Moloch's defeat. Acheri has began to gain momentum and gathering in strength in the closing years of the 41st millennium. An Adeptus Mechanium Explorator Fleet had recently discovered the Tyranid infestation on the verdant death world of Kerodan. A large planet which is considered by the Fleet where only the strong survive.
When the surviving bio ships limped away from Moloch's destruction, they turned on each other in a feeding frenzy as they had no hive ship to guide them to their next destination. The Eldar of Craftworld Erathlir destroyed all but a single cruiser. The cruiser showered Kerodan with Tyrannocytes and Mycetic spores carrying their lethal cargo. The bio ship died in orbit and the eldar warships dragged it into Kerodan's parent star. Burning the evidence while sending the Fire Dragons to burn the continent where the Tyranids landed on but did not destroy the planet all together. Though they did destroy every living thing on the continent, the surviving synapse creatures drove the remnants of the swarm underground or in caves. The others that didnt have any synapse creatures were burned to charred ruins. Thinking that the rest of Moloch was completely obiterated, Erathlir began to move on across the sea of stars, heading to an unknown destination.
Kerodan was a world immediately hostile to any race that tried to settle on its surface. To the Imperium, it is your average death world overrun by overgrown forests that blot out the sun, xenofauna big and small could eat them in unpleasant ways. The reason why it is a death world is because the plants produce a type of virus that spreads through spore dispersal. The fauna native to the planet are immune to its effects but is fatal to off-world species. At first, many tyranids died quickly from the virus