The Most Complete Guide to Maintaining Jack Dempsey Fish

Jack Dempsey Fish are a common sight in tropical aquariums and predatory aquariums. They come in all shapes, colors and sizes, each with their own behavior and personality. Jack Dempsey is one of the most famous and well-kept cichlids in the world. These fish are famous for their aggression and do not get along with other fish, but that does not mean they cannot be kept in flocks or even with other species.

Hobbies who know how to handle the aggressive nature of Jack Dempsey’s fish can create a pleasant aquarium environment, but those with less experience will have difficulty handling the behavior of these fish when bullying their seacarium friends. If cared for properly, this carnivorous fish will display a variety of beautiful colors and many interesting activities in your home aquarium.

Jack Dempsey Fish
Jack Dempsey Fish

Scientific name

Rocio octofasciata


This article will help you understand Jack Dempsey, from his behavior, appearance, ideal aquarium setup, food, life partner, and many others.


Jack Dempsey, or Rocio octofasciata , is a fish from the Cichlidae family. Most cichlids are from Africa or America. Jack Dempsey is no exception found in slow-moving waters in North and Central America, such as Mexico and Honduras. Cichlid has diversified quickly in this area.

They have now spread to the warm waters of Australia and Thailand, where they are known locally as Mexican blue frontosa fish. These carnivorous fish usually live up to 8-10 years, but can last up to 15 years if kept in a healthy environment. The price varies, depending on variety, size, and color.

How long can my fish live?

If you maintain all the necessary conditions for your fish to have a healthy life, it can live more than 10 years .



Typical of the cichlids, oval and corpulent, with the laterally compressed body, with the almost straight ventral line and large dorsal and anal fins, terminated at the tip (mainly in the male) and reaching the caudal fin, which is rounded.

The blue variety is the most appreciated in Aquarophilia and surprisingly it is not violent.

Jack Dempsey Fish
Jack Dempsey Fish


Dark gray base and covered with metallic blue and golden scales throughout the body. It has 7 or 8 clear transverse bands that disappear completely with age. In breeding season they turn almost black with macules of an intense metallic blue.

Young specimen of “Jack Dempsey”

The “blue” variety is metallic blue sky base, with dark blue metallic macules, which occupy the entire body and fins. The face is somewhat lighter in color than the rest of the body and has fewer spots. The macules are very variable in size and do not have a characteristic distribution pattern. In addition some fish have many more spots than others.

Aquarium conditions

Minimum measures for an adult couple of 100x30x35cm. They usually dig up the plants and dig in the substrate, so it will be convenient for it to be fine. Resistant and planted plants can be placed in protected areas, for example near glass or in pots, although this does not fully guarantee that they will not be displaced. Surrounding the stems with stones usually increases their protection. The Jack Dempsey are American cichlids, so unlike their African cousins ​​they will enjoy trunks and more acidic waters.

At what temperature should you have the water?

The optimum water temperature for Jack Dempsey is 26 to 28 ° C .

The temperature cannot be lower than 24º Celsius . In fact, you will realize that if the temperature falls below that scale, the fish will remain close to the heater.

Scientific nameRocio octofasciata, Cichlasoma octofasciatum
Common nameJack Dempsey, Electric Blue Jack Dempsey
Tank size200 liters
Temperature75-81 ° F (24-27 ° C)
size17 cm (6.69 inches)

Water conditions

They prefer neutral or slightly alkaline waters and of moderate to semi-hard hardness. pH between 6.8 and 8.0. GH between 5th and 18th.


They are easy to reproduce, their posts are made in open spaces and the relationship is of the “nuclear family” type. In the aquarium the female lays eggs on a large stone in the center of it.

Taking care of them, he positions himself on top of them, when someone bothers them the male stands in front of the glass as if wanting to obstruct the vision of the eggs, almost facing the observer. When the fry are born the same happens. It is common for them to move once they have hatched to the other side of the aquarium, something remote, hidden and on the sand, building a depression that can reach the glass at the bottom of the aquarium, and they deposit them there.


Behavioral traits

Many people do not like the aggressive nature of this species. Those who are not accustomed to raising aggressive fish may have difficulty caring for Jack Dempsey properly, so this fish is not recommended for beginners.

Jack Dempsey tends to be less aggressive in densely populated aquariums because they have difficulty in bullying one particular weak fish. The male will try to build a territory and will drive away other individuals. If you have lots of caves and gaps to form different territories, territorial conflicts can be slightly tempered.

They spend a lot of time hiding in the caves so they can look very shy. Most of them will live in the middle and lower depths of the aquarium.

Jack Dempsey Fish
Jack Dempsey Fish


The common name of these fish is based on their appearance. They have strong facial features and aggressive nature, similar to the legendary boxer of the 20s era, Jack Dempsey.

This species has a large oval body with long fins. Larger males with longer fins. Their popularity is largely triggered by the beautiful variety of body colors. There are many varieties, but the most popular are gold, blue and pink.

The color of Jack Dempsey varies from one individual to another, mainly because the color changes with age. Young fish are pale gray with green spots, whereas adult fish turn into dark purple gray with bright blue-green spots.

Color can change for a while. They will turn pale when stressed and become dark when mating. You can see their fins to distinguish their sex. Males have long dorsal and anal fins with pointed tips, while females have shorter, less prominent fins.

There is a popular blue variety of this species known as electric blue Jack Dempsey. This variant is slightly smaller and less aggressive.

Jack Dempsey fish will grow between 25-40 cm and females grow a little shorter.

Natural habitat

In the wild, Jack Dempsey fish live in various slow-moving freshwater waters. This includes murky rivers, canals, lakes, and swamps. They prefer a tropical climate, so they are accustomed to warm water that is slightly acidic with low lighting levels. Their environment consists of a sandy and muddy substrate with rocks and debris on it. Plants also spread around it.

Aquarium setup

Starting at the bottom of the aquarium, choose soft sandy substrates because Jack Dempsey likes to spend a lot of their time in low waters. When adding decorations, make sure you have plenty of caves scattered around the aquarium so fish can search and claim their own territory.

You can also add plants because Jack Dempsey won’t usually destroy them. But one day they can decide to dislike plants in the aquarium and begin to destroy them. Make sure no other species in the aquarium like to destroy plants.

They need a heater to maintain warm temperatures between 22-30 ° C. The pH must be 6-7 and the water hardness is 9-20 dGH. Air or water pumps are not needed because they prefer slow-moving water, you only need a good filter to make a little current. Avoid bright lights or Jack Dempsey will just hide. Their natural water is a bit murky, so use a low light. Floating plants (such as hornwort) can be used to shade certain areas.

Maintaining Jack Dempsey in a large aquarium is important because a small aquarium will provoke their territorial tendencies. This fish needs at least an 80 gallon (302 liter) aquarium. Each fish needs at least 55 gallons (208 liters), but they will be happier if more space is provided. Remember these fish are aggressive and need their own territories, that’s why give each of them a place to hide.

Aquaculture friend

Jack Dempsey’s aggressive nature can limit other types of fish that are suitable to be mixed with him, but that does not mean there is no choice at all for him. The aquarium pair generally must have the same size and aggressive temperament. This means that no fish can fit into the mouth of other fish and all fish can defend themselves

Peaceful species will be bullied, even to death. Small fish like tetra will only be treated as food by Jack Dempsey. Oscar fish is a popular choice such as cichlid mbuna. Other options include angelfish, birchir, blue event, clown loach, convict cichlid, firemouth cichlid, plecostomus, and silver dollar. Invertebrate animals such as shrimp and snails are very popular in tropical aquariums, but they tend to be seen as snacks by Jack Dempsey.

Putting Jack Dempsey together in one species-specific aquarium is the best choice for beginners because it is difficult to keep other species alive with Dempsey. The thing to remember is that males do not tolerate the presence of other males very well, so one male per aquarium is the safest choice.


As a carnivorous fish, Jack Dempsey’s food usually consists of anything that can be put into his mouth. They can quickly prey on worms, crustaceans, insects, and small fish. There are many choices to feed them at home aquariums. They are not picky eaters so you can choose what is easiest for you.

Processed dry foods are generally cheaper and widely available. You can buy pellet feed and flakes specifically designed for cichlids. If you want to use processed foods, choose frozen / live foods to give to the fish occasionally. This will increase their nutritional intake.

Popular live food choices include blood worms and salt water shrimp. Large insects such as crickets, grasshoppers and fruit flies are also suitable for your Jack Dempsey. Herbivorous food will largely be rejected, which is why you can put living plants in an aquarium without worrying about being eaten.

Feed adult fish 1-2 times a day. Give food in a measure that they can spend in two minutes. Teenage fish need to be fed a little more often, 2-3 times a day, to help them grow.


Jack Dempsey has simple maintenance requirements. Problems will arise if you make a herd or mix it with other species. Dealing with their aggression can be difficult if you have never maintained aggressive cichlid before. If handled badly, your Jack Dempsey will start bullying each other and other species.

If aggression is handled properly, it is not difficult to keep them healthy. However, they can be affected by diseases like all other freshwater fish. One of the most common problems is ich (white spot disease). These are ectoparasites which appear as white nodules on the body and fins. Increasing the temperature of the water in your aquarium to 30 ° C can help treat this disease.

Another common disease is Head and Lateral Line Erosion (HLLE). This disease forms a hollow or hole in the head. This is usually caused by malnutrition, so you have to change their diet if fish experience it.

An unhealthy environment usually triggers disease, so you must maintain aquarium cleanliness. Anything you add to a stable aquarium can bring disease so quarantine is a must.


When a pair of Jack Dempsey is ready to mate, their color will darken. If the male is ready to mate but the female is not, the female can be bullied to death.

Water conditions must be near perfect for spawning to begin. Water must be clean and within the ideal parameters described previously. Temperature at the higher end of the range (28 ° C) is a good trigger.

Large males will be more successful in seducing females (this is common in many cichlids). After mating occurs, around 500 eggs can be produced. The eggs attach to a flat surface nearby such as decorations, substrates, or aquarium walls. After three days, the eggs will hatch.

Parents are quite considerate of the king. They dig holes in the substrate to protect the birds until they can swim freely. Both mother and father will share the task of looking after their babies. They even destroy food and release it for food to be eaten until they are old enough to find their own food.

If parents are stressed by poor environmental conditions, they will begin to eat fish so they need to be separated.


Every aquarium is different, but most stable tanks will not be able to accommodate a new group of Jack Dempsey. This Cichlid needs an aquarium designed specifically for them.

This is mainly due to their aggressive nature. Jack Dempsey is not a fussy fish species. As long as the aquarium setup is running well, they are relatively not too difficult to maintain. They are also not fussy about food and will receive most of the same food as other carnivorous cichlids.


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