First of all, did the poster tighten the cap when putting water in the mineral water bottle?

We need to clarify the purpose of drying the water, which is to evaporate the chlorine in the tap water, otherwise it will cause certain damage to the respiratory system of the fish. If the bottle doesn't have a lid, it's fine. If the lid is screwed on, the water will look like it hasn't been exposed to the sun.

We are looking at the living environment that betta fish likes. Betta fish likes to live in places with lush aquatic plants and plenty of shelter. The conditions created by the poster for it are exactly the opposite. Besides, the temperature has reached 32 degrees. Although 32 degrees is theoretically acceptable for tropical fish, direct exposure to the sun is definitely not good for fish, and the fish may die of heat.

Let’s talk about the problems caused to the fish by the owner’s move. There are generally not many balcony decorations, not to mention that the owner’s balcony is open-air, so it is unlikely that the fish died due to decoration pollution.

Looking at the state of the fish’s death described by the poster, it can be concluded that the betta fish died due to excessive water temperature caused by direct sunlight without shelter.