Southern fish was the name for Piscis_Austrinus in the original translation of the VAT and preceded the change later to the Swallow. Here is from the original translated to English by Ann O'Maly
2. Saturn opposite the southern Fish of the Zodiac. On the morning of the 2 nd , a
rainbow formed an arc in the west. On the night of the 3 rd , the moon 2 cubits in front
of [...].
Reference:
Ein astronomischer Beobachtungstext aus dem 37. Jahre
Nebukadnezars II (-567/66)
By Paul V. Neugebauer and Ernst F. Weidner.