Lurking in the depths of a 40,000-liter fish tank within the Paris Aquarium is an unlikely sight—one that many visitors might be surprised to see. The freshwater tank is just one of several that house the aquarium’s growing population of goldfish.

Over the past few years, the aquarium has become a refuge for unwanted goldfish, providing a second life for any unwanted pets who might otherwise find themselves flushed down the toilet – a trip they most likely won’t survive.

Typically, parents would bring in goldfish after their children won them as prizes at local carnivals. But what starts out as a pretty pet often becomes a nuisance for many people, since they’re not quite sure how to properly care for them. On top of that, many Paris homes simply aren’t large enough to house fish tanks equipped with filters that are the appropriate size for goldfish.

Rather than force these pets to an untimely death, the aquarium began adopting them instead, with people bringing them to the aquarium in tanks, buckets or any receptacle they can transport them in. Apart from saving the little guys, the sanctuary has also become an educational resource for the aquarium to teach people about the harm that releasing them into the wild can do, both to the environment as well as to the goldfish themselves.

Four years since the sanctuary was created, the aquarium now hosts more than 1,000 goldfish, 600 of which are rescues, and the number continues to grow as hardly a day goes by without a local resident dropping off an unwanted pet.