The salty water is mixing with the fresh water springing in several places of the moat, and this created a unique ecosystem, in these moats living together both fresh and salty water fishes.
EXIF info:
Nikon Df
Lens: 24-70mm F/2.8G
Focal Length: 24mm
Aperture: F/7.1
Shutter Speed: 1/1000s
ISO Sensitivity: ISO 400