London zoo breeds endangered Banggai cardinalfish

by ZSL on

Two black and white cardinalfish adults showing breeding behaviour

Banggai cardinalfish threats

In the wild, Banggai cardinalfish numbers have plummeted. Their surging popularity in the aquarium hobby sparked a goldrush in overharvesting, with fish bombs made from cyanide, fertilisers and phosphorus used to stun and catch as many as possible. The precariousness of the Banggai cardinal population is confounded by their small native range in Indonesia of 5,500km2, around the size of Venice! As a result, their numbers in the wild has decreased by more than 80%. This makes every new arrival vital to establish a back-up population, but breeding Banggai cardinals is tricky.  

Cardinalfish adult in an aquarium

Banggai cardinalfish breeding

Unusually for marine fish, Banggai cardinals only raise a few fry (baby fish) at a time. The male protects the fertlised eggs by carrying them in his mouth until the eggs hatch, and from then on, the fry are on their own. These tiny fry require microscopic foods to survive, which our Zookeepers must carefully cultivate to keep them going. In the wild, fry survive by hiding between sea urchin spines, which is thought to be the reason for their striking black and white camouflage. Our zookeepers replicate this by creating artificial urchins to ensure they feel secure. Once large enough, our fry are added to our seven-metre-long reef aquarium at London Zoo’s Tiny Giants.

A black and white cardinalfish fry in an aquarium at London Zoo

Coral reef fish conservation

At the Zoo they are ambassadors for their species, raising awareness for the importance of sustainable practices in the pet industry. We’re also advancing aquarium breeding success of more species that are key to the ongoing health of coral reefs in collaboration with Bangor University. Together we are collaborating to raise species that have never been successfully bred in aquariums before. The support of Players of the People’s Postcode Lottery is helping us raise future generations of endangered coral reef fish.

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