My Water Garden Pond - Looking for Suggestions

Hi All,

I need H-E-L-P...

Here is a picture of the rock and the beginning of my water garden pond.

I want to use a flexible liner and use the rock as a waterfall.

I haven't decided on fish yet. But open to any suggestions.

I've helped put up [above ground] swimming pools and install in-ground swimming pools - my friend has a business that I help out with.

I'm sure that ponding has many similarities - and probably a lot of differences. :-)

Although I've started this, before I continue I would appreciate any suggestions and thoughts to this undertaking.