Well then it's nature everywhere since there are natural things everywhere. But generally we like to see nature as something that lacks artificial/modern elements (or at least under an arbitrary threshold). As for the fish, I agree that it is natural. The environment shown in the other pictures makes me wonder if the cause of its death is all that natural, that's all.
Yes it was. We were following a creek. It had isolated pools that were drying up and fish were caught in them. We encountered many dead fishies along the way.