Seven Keys: Stuck

Hi lads,  I've been completing all the missions recently and I finally got to the last mission, seven keys. I have to say it is a pain, i got to the fourth part of the mission where you have to get the fish which dies when it's taken out of water and I literally have no idea how to get her to the portal/circle where the other keys are suppose to go. So does any one of you finished that mission and could give me a hand of advice on what should I do? Thanks

Where does it spawn again?

You need to construct a water way so that the fish does not die. You can also kill it and then it spawns maybe in a more favorable position (save game before testing this).

It spawns in water, pool, sea etc.

As Maikel said, you have to construct a waterway up to the portal(?). Either with lots of loam bridges or by blasting through the middle of the pillar and them pumping water into it.

Seven Keys is designed to be hard and ridiculous. Keep that in mind.