This is fantastic. The texture and light are perfect imo. The only thing that concerns me, and I understand the limitations of basic editing, are the white dots in the upper right hand corner. they upset the 'low key-ness' of the photo. in any case, a well deserved 8.
Beautiful! I can see scales on the fish and ripples on the water's surface, but the light in the water quickly dissipates into darkness. Really cool use of low key.