Achelois was one of those Greek Moon Goddesses, but was mostly known as ‘She who drives pain away’, as she had been consulted because of her healing skills. She’ll throw away your headaches if you make a appropriate sacrifice. However, in accordance with Tzetes, she had been among those Muses, daughters of Pierus.
The Sirens, the daughters of Achelous surname were Achelois. Achelois was an overall name for water-nymphs, as in Columella, in which the companions of these Pegasids are known as Acheloides.