Perhaps they are being true to the picture posted and using the biOrb (think that's what that is) so maybe they're not killing hundreds of fish in a week. Also because there are specific "fish therapy rooms" customers can request and not "fish in every room." Also, if you read the article, it says the favorite pet fish in the UK is the goldfish. But yes, they are cheap and easy to replace, etc.
1 yoyo loach, 2 polkadot loaches, 6 cherry barbs, 2 turquoise rainbows, 1 chinese algae eater, 2 harlequin rasboras; java fern, java moss, hornwort, Asian ambulia