This image portrays an exodus of a civilization. Could be ours someday... There is a feeling of peace and the sunset represents hope of a new beginning.
Regarding the spaceships, there is an analogy with fish both in their design and in the way they are grouped together as in a school of fish.
This image was done for a portuguese forum contest whose theme was "Grand Space". It was done in Photoshop with a little help from 3dsmax (spaceship mockups) and took me about 20 hours to complete. No photos or photo-based brushes were used as it was one of the contest rules.

Here are a couple of details, the painting process and a version without the spaceships:

DetailA
DetailB
DetailC
DetailD

Process

Landscape