Integrating the exhibits into the environment allows for a highly complex natural experience for the animals and the visitors. Visitors see fish as part of nature rather than isolated in a tank in a building.
Plants grow healthily and plantings can be incorporated into the design - in fact, the landscape is integral and a highlight of the design. Animals in the exhibit experience a more natural life - they have access to the open air and the weather, natural light, and insects and birds may visit their water body.
Traditional aquariums are usually indoors and the cost of the building is exponentially greater than the cost of an outdoor tank exhibit. Corrosive saltwater further drives up the cost of any building material surrounding a tank.
Outdoor, landscaped aquarium exhibits are not often a consideration for a new design because they don't allow for complete control of the parameters of the exhibit. Algae growth is often cited as a problem, but I spoke with aquarists at an outdoor exhibit in Abu Dhabi and they said they experienced less growth in their outdoor tanks.
In Oregon along a hiking trail this viewing window is set into the side of a naturally flowing stream. It was not a captive fish exhibit and when I was there there weren't many fish to see. But I was told one can observe larger trouts here.
https://youtu.be/u1xc4odhBWM
At the Pilsen Zoo in the Czech Republic fish tanks presenting a stream habitat are viewed from the side in a cutaway tank. The surrounding area is landscaped.
The first video shows unfortunate reflection that occurs when the screen (and the observer) aren't in the shade.
Reflection
https://youtu.be/JyjUNbEi_SI
But there is also this larger tank that the visitor sees from inside a grotto. The fish can enjoy the sun, wind and rain. The visitor can enjoy a perfect reflection-free viewing experience. It's great. The windows are narrow, which keeps the glass thin and prevents a green hue.
Pilsen Zoo, Outdoor fish tanks.
https://youtu.be/R1kDRgSyuVo
https://youtu.be/O3JqIYCPF_g
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| The visitor is standing in a grotto, the fish swim under open sky. No reflection issue here. |
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| Again, no reflection issue. |
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| A bit more shading on the visitor side and this would make a perfect viewing experience. |
At Cleveland Zoo in Ohio the visitors are under a covered area and the fish are not - it can rain and snow into the tanks while the visitor stays dry. The photos below were taken during a heavy downpour with thunder and lightning.
Birds and insects can enter the exhibits. Which might need consideration.
A cutaway view offers a unique view into the animals' habitat. Everyone has experienced looking into a pond or stream from above.
Here's a great example from the Sea Life Park in Tokyo. It rained that day, too. But I'm standing in a covered (but unheated) building. The viewing was excellent.
Sea Life Park Tokyo
https://youtu.be/AeZcT2qUPP8
The large tank with the greenish hue, was covered in a net that was barely visible to the visitor. Unfortunately the tank was poorly stocked. Only a few and small fish.
But the last 3 feet show a beautifully decorated tank with an excellent viewing experience.
Below: many more photos of outdoor tanks. Some are within a netted area, an aviary; good to keep birds in, and other birds out. Here the net is nicely hidden from view by the lush vegetation.
This photo is taken from inside a greenhouse, with the visitor being inside, and the fish tank outside.
Below more photos that show outdoor tanks. Either as cutaways or as ponds.
