The London Zoo is urgently seeking a female mate for the last-known males of a critically endangered fish species.
Zoo officials say the Mangarahara cichlid is thought to be extinct in the wild and that two of the last known individuals — both male — are in the zoo's aquarium. A third is in the Berlin zoo.
Officials say the species' habitat in Madagascar has dried up due to dam construction.
The zoo on Friday asked aquarium owners and fish collectors to come forward it they know of any living females "so that a vital conservation breeding program can be started."
Officials say a worldwide search of zoo and aquarium organizations has so far proved fruitless.