Banggai cardinalfish: Very protective dads

There are thousands of marine animals around the Aquarium—some are small, some are shy and some have unusual lifestyles, at least by human standards.

Take the Little Banggai cardinalfish, (Pterapogon kauderni), for instance.

 
Banggai cardinalfish in the Aquarium's Living Corals exhibit

You can find this species in the “Living Corals” exhibit, (the tank closest to the Gift Shop on the first level). Native to the Banggai Islands of Indonesia, its good looks and ease of breeding make it a popular species in the aquarium trade. Popularity has also created a challenge for the species in the wild—it is currently listed as an endangered species on the IUCN red list.


Male Benggai cardinalfish carrying eggs in his mouth

This is a small, but elegant animal. Look for the fish that appears to be ready for a black tie event, with his black stripes and dramatically forked tail. He sports a sequined gleam and stylishly tasseled fins, sprinkled with decorative white dots. Practically speaking, the cardinalfish’s glamorous attire is suited to his life camouflaged amidst sea grasses, anemones and the long, black spines of the mildly venomous urchin, Diadema.

 
Follow the arrow to see the eggs sitting in this father's mouth.

Now look a little closer—he might not only be ready for a formal night out, he might also be ready for a visit to the maternity ward! If you see a fish with a distinctly larger jaw, you may be looking at a male brooding his young. He has a large oral cavity to accommodate the eggs and young that he nurtures attentively.



In fact, this father doesn’t need the maternity ward for help birthing; he does just fine on his own. You may see him roll the pinkish eggs to rearrange and oxygenate them. Once the eggs have hatched you may even see some tiny eyes peeking out when the male stretches his mouth. As the fry grow and are more difficult to contain, you might see a flurry of fins emerging from the male’s bulging mouth.

When his favorite food is presented in the exhibit, you may see him scurry—in the opposite direction! He doesn’t want to risk any of his young escaping his protection and becoming part of the food chain. In this way he protects his brood of up to 25 young for about 4 to 5 weeks, without ever taking a meal himself. Phew! After that, he might really need a night out!



The aquarists who take care of this exhibit leave a fry collector in the tank overnight in the attempt to catch these babies. We'll update you more on these efforts another time. Stay tuned!

– Lisbeth