Our feature species this month was chosen by senior aquarium biologist, Jennifer Reynolds. She chose the cuckoo catfish because it “has a fascinating reproductive story.” This attractive looking fish is a parasitic mouth brooder.
This freshwater catfish is endemic to Lake Tanganyika, Africa, and listed as “least concern” by the International Union for Conservation of Nature (IUCN) because it’s abundant. This fish eats snails and other bottom-living invertebrates in the lake.
There are many other fish that share Lake Tanganyika with the cuckoo catfish, but the one that plays an integral role in the catfish’s life is the cichlids. While a pair of mouth-brooding cichlids are spawning and laying eggs, a female cuckoo catfish will eat the cichlid’s egg and deposit its own eggs in its place. Because she incubates her eggs in her mouth, the female cichlid picks up her eggs and (unwittingly) the eggs of the cuckoo catfish and incubates all of them in her mouth.
The cuckoo catfish eggs develop and hatch first, and take advantage of their faster developing time by feeding on the still-developing cichlid eggs. This incredible breeding strategy is a great way for Jen “to explain to guests or new staff members why she studies freshwater fish.”
Jen says, “I remember the thrill when Lee Newman-curator of Tropical Waters-and I found the first baby cuckoo catfish. We’d been removing some of the other cichlids from the exhibit as they had been breeding prolifically. Then, there it was. A tiny cuckoo catfish swam out from under the rocks. I gasped and knew right away what had happened. We gave it a special little rearing container in the back where I could keep an eye on it, and it was really one of the cutest baby fish I have ever seen. Since then, we’ve had this happen in the exhibit a few more times. It is always a special thrill for me when I see a tiny cuckoo catfish emerge from the rocks.”
Find the Cuckoo Catfish in the Tropic Zone at the Aquarium.