This origami base is really just two Rabbit Ear Folds.
1) Start of by folding a square of paper in half diagonally.
2) Do a Rabbit Ear Fold on one side.
3) The completed Rabbit Ear Fold.
4) Do another Rabbit Ear Fold on the other side.
5) The completed Fish Base.
If you open the model up you’ll see the following Mountain (black) and Valley (red) folds.