Synodontis acanthomias is a species of upside-down catfish native to the Congo Basin of Cameroon, the Central African Republic, the Democratic Republic of the Congo and the Republic of the Congo. It was originally discovered by George Albert Boulenger in 1899 in Boma, in the Democratic Republic of the Congo. The original specimen resides in the Natural History Museum in London. The species Synodontis pfefferi, described by Franz Steindachner in 1912 was found to be the same species. The specific name "acanthomias" means "very spiny", a reference to spines found on the side of the fish's body.