Docimodus evelynae Eats the Nose Warts of Neighbouring Fish

Docimodus evelynae is a cichlid from Lake Malawi which is known for its peculiar eating habits. Not content with eating anchor worms, fish lice, and fish fungus as juveniles, adult evelynae have been reported eating scales (a practice known as lepidophagy,) as well as the skin of other fish, attacking Bagrus meridionalis and Clarias gariepinus catfish in particular. However when researchers in Japan examined the stomach contents of this known scale eater they found some 1mm hard white warts. The warts were the snout tubercles of an African cyprinid called the Redeye Labeo, Labeo cylindricus and what’s more, these pimples, or “pearl organs,” were making up 15% of the diet of subadult Docimodus. 

“Pearl organs, never reported as a primary food for fish, could offer a substantial nutritional source based on calorific calculations.” said the paper’s authors. “Understanding how this peculiar diet is foraged is essential for full comprehension of the food-web structure in this lake.”

Scale eating is already known in the fish world, with a characin called Roeboides affinis known for it, as well as Perissodus and Plecodus cichlids in Lake Tanganyika. There are fin eating characins too, but Lake Malawi’s Docimodus evelynae is up there with the best of them. Part cleaner fish, part parasite, and one Malawi cichlid you wouldn’t want in the home aquarium.  

Read the scientific paper

Takeuchi, Y., Hata, H., Sasaki, M. et al. Preying on cyprinid snout warts (pearl organs) as a novel and peculiar habit in the Lake Malawi cichlid Docimodus evelynae. Sci Rep 14, 19300 (2024). https://doi.org/10.1038/s41598-024-69755-z