As a regular breeder of J. dickfeldi, I spend considerable time observing them. Of the many interesting behaviors they exhibit, perhaps one of the most is their propensity for house cleaning.
One of my breeding pairs spawns in a ceramic tube that is rectangular in shape. It’s closed on one end, and I use a rock or other object to partially block the open end. The tube is about 6″ long, more than long enough for this smaller Julie species, but maybe a little tight for larger Julies like regani.
When the dickfeldi are getting ready to spawn, the male will remove detritus from the tube with his mouth, much like shell dwellers move sand around their shell. This is an interesting behavior that I have not witnessed in another genera. However, I suspect it is not unique to dickfeldi species within the Julidochromis genus.
Dickfeldi are opportunistic cave breeders in captivity. They will utilize what is available to them that offers the most protection for their eggs. I give my breeders caves and other tight structures to both give them options and to ensure that they have something suitable for spawning.