* Whales are far too large: Even the smallest whale species, the dwarf sperm whale, is still much larger than any aquarium.
* Whales are marine animals: They require vast amounts of ocean water, specific salinity levels, and constant movement. A tank simply cannot provide this.
* Ethical concerns: It would be incredibly cruel to confine a whale to a small space, even if it were technically possible. Whales are highly intelligent and social creatures with complex needs that cannot be met in captivity.
* Legal restrictions: It's illegal to capture and keep whales in captivity in most countries.
In short, it's simply not possible and it would be incredibly harmful to try.