3.
(for those who had issues with this, the new rules were not in place when it was submitted/the month the contest ran, so there is no violation of the rules when it was entered)
That's a hard choice. I like the lighting and P.bass in pic.2 but I prefer the scape in pics.1 and 4. I dont think 3 is the photographers tank so that one is moot to me (sorry if I'm wrong about that).