Which of the following options is the best substitute for the underlined words in statement III?

Directions: This passage contains errors and an omission. Choose the correct option to complete the passage.

Statement I: Manish and Jimmy were been in Bangalore for a day only.
Statement II: Today they are going to the aquarium.
Statement III: Aquariums are places where different kinds of fish are kept for breeding.
Statement IV: There are big glass tanks for the fish. The water in these tanks _____