Martin was not convinced that it is possible to identify the exact river clearly, although he suggested that it might be the river presently known as the Edhessaíos, on the basis of an 1829 map.
This theory seems unlikely, as in Ælian’s time this river was known as the Scirtus and there is no compelling reason why he should not have known of it, not least because of the problems it caused with its periodic flooding of the Via Egnatia, of which more later.
The only clue to the river's position was that it was "Between Berœa  and Thessalonica." During the past few decades there have been many attempts to identify which modern river can claim to be Ælian's Astræus, but this research has been difficult and from a reading of published work it is still not clear which river it might be.
This is our attempt to summarize the literature to date and to bring more light to the subject. One candidate is the mythical god called Astræus, a son of a king Hippotes.
In his short, but very comprehensive paper Hammond rejected two earlier theories about the identity of the Astræus: that it was either the Axios or the Aliákmon rivers .