https://www.mpg.de/26360211/0410-psy-underwater-architects-how-do-shell-dwelling-cichlids-build-the-perfect-nest-155111-x
How do shell-dwelling cichlids build the perfect nest?
The individual steps of nest-building are instinctive, but only through practice do the fish become true masters.
shelldwellingcichlidsbuildperfect