"Sea Change" by Len Kaminski, Javier Saltares, and Mark Propst.
This was one of the half-dozen alternative JLA one-shots released at the time, featuring Aquaman (yay!) leading his own version of the team, this time with Atlantis-based heroes.
In the battle versus a magical being known as Devilfish, this JLA meets another JLA--the Justice League of...Apostles?:
...I wonder if the Stranger was as dodgy about being a member of this JLA as he was the regular one!