Extinction of the Aboleth

When the Mortal Realm was newly formed, before even the gods had discovered this new plane, the Aboleth where there. These tentacled monstrosities would swim the oceans and rivers of the primordial world and seek out any burgeoning life to subdue and enslave.
When the gods did come, however, they saw the injustice this race of aquatic horrors were invoking on their subjects and set out to eradicate them all.
Although it has been Age's since anyone has seen an Aboleth, rumours are always being heard that they are not yet extinct.