Ignoring the fact that bowls aren't actually good for fish in general, either way that runs the risk of introducing bacteria into the tanks, temperature variations, a complete lack of shelter for the fish once it's in the bowl (unless there's no shelter for it in the larger tank, which is even more troubling), a lack of aeration (and filtration), as well as isolation and stress on the fish, both in putting it in the bowl/transfer, and in returning it to that tank. It's also, again, entirely too small a bowl for a fish that size, not to mention it has no lid-- and some species of fish are quite willing to throw themselves OUT of bowls like this when they're stressed or find them too small. That bowl isn't even large enough for a Betta to spend any length of time. And that's also assuming the person renting the fish isn't uneducated or an ass and puts something dangerous in the bowl.
I would not be surprised if this hotel has a very high turn over rate of fish
€3.5 per night for the fish only, another €3.5 for the bowl and water, add €1 for ornaments if you want. Additional €5 fish food mandatory for each rent. Profit!
I would not be surprised if this hotel has a very high turn over rate of fish
the point. Speeding by waaay over your head