Garden Tub In A Bay Window Urgh. Pond Fish Dead. Thoughts As To Why?

Urgh. Pond fish dead. Thoughts as to why? - garden tub in a bay window

I am creating our bathtub pond. 35 gallons, about 1.5 meters deep, 3 feet wide.

Add water from a garden hose and a little water placed in a pond, rocks, some plants. Fish .... put on standby. Today, they are all swimmers. Guppies luxury 3, 4 comet (feeder fish). Survived only our turtle.

We are just south of SF Bay in California. The time is not so cold at night. We opened all the windows at night to cool the house.

What do you think went wrong?