Blue Dempsey: Characteristics, reproduction, care and more….

Let´s meet the striking Blue Dempsey, Rocio octofasciata or blue Nandopsis Octofasciatus in scientific terms.

Blue Dempsey which belongs to the cichlidae family (bony fish), are hybrids and descend from the Jack Dempsey fish. They were known thanks to the uruguayan Héctor Luzardo, as a result of a genetic mutation. The adult specimens show a magnificent blue coloration that dazzles any one.

The Blue Dempsey’s Main Characteristics 

This dazzling fish is a natural variant of  the Jack Dempsey. Their body is oval and laterally compressed. Their dorsal and pelvic fins are long and end in tips, usually surpassing the caudal fin (mainly in males), which is rounded. We invite you to read our article the anatomy of fish, to learn more about this topic

The blue metallic sky color of their body, with dark metallic blue macules, is a disticntive trait of this species. As for their face, it´s slightly lighter in color than the rest of the body and has fewer stains.  The macules are very variable in size and lack a characteristic distribution pattern. In addition, some specimen have many more stains than others. Their size  ranges between 20-25 cm.

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Blue Dempsey’s Common Behavior

These fish are quite peaceful (unlike their ascendant the Jack Dempsey), which makes them suitable to share the aquarium with other peaceful species of similar size and quiet customs. However, it´s not recommended having them with too small species since they could confuse them with food.


They don´t inhabit nature as a result of their captive breeding.


It´s quite difficult to achieve due to the mutation from which them originate.  However, their reproductive method is very similar than that of the “Jack Dempsey » (C. octofasciatum). Once a couple has been set, they clean an area of the aquarium keeping away any intruder. Then, the female lays the eggs in a smooth stone and the male fertilizes them. In 72 hours the fry are born, who will be cared for by their parents.

The offspring can be fed with infusions, nauplii of artemia (brine shrimp) or pulverized commercial foods type micron (exclusive for Ovíparous). When they reach 1 cm in length it´s advisable to separate them from their parents, since if there is no space and sufficient hiding places they could kill each others.

Sexual differences:

There aren´t big differences between both sexes when they are juvenile. However, during adulthood males tend to be larger in size than females and darker in color. On the other hand, females have shorter and rounded dorsal and anal fins. These differences are noticeble only in adult specimens

Blue Dempsey in Aquariums

The Blue Dempsey is very easy to take care of as long as the water remains clean. Keep in mind that aquariums are closed systems and regardless of their size, they all need some maintenance. In domestic aquariums, nitrate and phosphates accumulate over time and the water hardness increases due to evaporation.

Since these fish are very sensitive to contaminants and unstable pH, it´s  important that at least 15-20% of the water in the tank is replaced twice a week, especially if the tank is densely stocked. When making the water changes, always use a gravel cleaner to make sure that all decaying organic matter that has accumulated is removed. Most of the problems that occur with tropical fish tanks are usually reduced to one cause, decomposing organic matter.

The following conditions must be fulfilled in order to keep them confortable.

Water: PH between 6.8 and 7.4 and a hardness of 10-12 º D.

Aquarium: From 200 liters for 2-3 specimens, with many plants. It´s very advisable and common to employ a dark substrate to accentuate their striking coloration.

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