Jack Dempsey fish: Care, lifespan, breeding and tank mates

Jack Dempsey fish is a cichlid species that is widely distributed throughout North and Central America (south of Mexico to Honduras).

Here is a fun fact:

“Its common name refers to its aggressive nature and strong facial characteristics, similar to that of the famous boxer Jack Dempsey of the 1920s.”

Cichlids are a common occurrence in tropical aquariums. They come in all shapes and sizes, each with its own personality and behaviors. Jack Dempseys are among the most famous cichlids. 

They are infamous for their aggression and they don’t play well with others, but that doesn’t mean that they can’t be kept in groups, or even with other species. 

Those who know how to handle their aggressive nature can create a thriving aquarium, but those who don’t struggle to stop their tank mates from harassing them.

This carnivorous fish, if properly kept, introduces different colors and plenty of activity into your tank.

Overview of Jack Dempsey fish

This article will help you get to grips with Jack Dempseys covering their ideal setup of tanks, preferences for feeding, mates of tanks. 

Jack Dempsey, or Rocio Octofasciata, is a family of Cichlidae fish. Most of the cichlids are African or American.

Jack Dempseys are no exception and are found across North and Central America in slow-moving waters like Mexico and Honduras. Cichlids were rapidly diversifying in those areas. 

They have now settled in Australia and Thailand’s warm waters where it is locally known as the Mexican Blue Frontosa. 

This carnivorous fish usually lives up to 8-10 years, but if kept in a healthy environment, it can survive until 15 years of age.

Most pet stores sell them for $5-10 – though rarer varieties may cost a little more. If you have a particular variety in mind, it may be a little harder to find a particular color.

Typical Behaviour

The behavior of Jack Dempsey fish is quite hard to handle with as they are quite very aggressive in nature. Hence handling this fish is quite hard for beginners.

The aggressive nature of this species puts many people off. Those not used to keeping aggressive fish may struggle to care for them properly, so beginners are not recommended. 

In well-populated tanks, they tend to be less aggressive because it is harder for them to stand out and pick on stray fish. 

A male will try to establish a territory and fend off other people. If you have plenty of caves and crevices to form various territories, there will be few disputes over the territory. 

In these caves, they spend a lot of time hiding away so they can seem quite shy. They will mostly remain in the middle and lower tank levels.


Appearance of jack dempsey fish
Image by Jason Wolff from Flickr

This is how the appearance of jack Dempsey fish. This species has a big oval body and long fins. Males are going to be bigger, with longer fins. 

Its popularity is due in part to the range of colors in which you can find them. There are lots of varieties but golds, blues and pinks are the most popular. 

The color will vary between individuals, especially since their color changes as they age. Younger fish are pale gray with green flecks, older fish with bright blue-green flecks become a dark purple-gray one.

Colors can change temporarily-pale when stressed and dark when mating. To sex them, you can look at its fins. Males have long dorsal and anal fins with punctuated tips, females have shorter, less pronounced fins. 

There is a popular blue variety of this species that is known simply as the very good looking electric blue Jack Dempsey. In fact, this variety is less aggressive and slightly smaller.

Here is how an Electric Blue jack Dempsey fish looks like

Electric blue dempsey fish
Image by Michael Watson from Flickr

Jack Dempsey Habitat and Tank Conditions

You’ll find Jack Dempsey fish in the wild living in a range of slow-moving freshwaters. This includes turbulent rivers, canals, lakes and marshy areas. 

They prefer tropical climates, so warm waters are used to them. At low light, the environment would be slightly acidic. 

Their surroundings would be a sandy, muddy substrate that sat on top with rocks and debris. Plants would too be scattered around.

Tank setup

Starting from the bottom of the tank setup, pick a soft sandy substrate as Jack Dempseys spends a lot of their time in the lower water levels. 

Assure that you have multiple caves spread around the tank when adding decorations so that your fish can find and claim their own territories. 

You can also add plants since they usually don’t destroy them. However, one day they may decide they don’t like the plants in the tank and have destroyed them. Be careful to check that any other species that you retain will not destroy either. 

To keep a temperature between 72-86°F, they’ll need a heater. The pH should be 6-7, and the hardness of the water should be 9-20 dGH.

There’s no need for an air or water pump because they prefer slow-moving waters, you just need a filter to generate a slight current. 

Avoid the bright lights, or just hide your Jack Dempseys. To use some dimmer lights, their natural water would be slightly turbid. Floating plants (such as hornwort) may be used to shade some areas.

Tank mates for Jack Dempsey fish

Tank mates? Yess!! Finding the right and ideal tank mates for Jack Dempseys’ plays an important role when it comes to when you plan to acquire this fish in your aquarium. This is due to its aggressive nature can be quite restrictive when looking for tank mates, but that doesn’t mean that there aren’t some good options out there. 

Tank mates with the same aggressive temperament generally need to be similar in size. This means that no fish can fit into the mouth of another and that everyone can defend themselves. 

They will harass peaceful species, possibly to the point of death. Small fish such as tetras are only to be treated as food. 

Both Oscar fish and Mbuna cichlids are a popular option. Other options also include

Invertebrates such as shrimp and snails are popular in tropical aquariums but are likely to be seen as snacks.

Feeding your Jack Dempsey

As carnivorous fish, a diet for Jack Dempsey would normally consist of anything meaty they could fit into their mouth. They can grab worms, crustaceans, insects and small fish very quickly. 

There are many possibilities to feed them in a home aquarium. They aren’t picky eaters so you can choose the easiest option for you. 

Dried foods that are processed are usually cheaper and readily available. Pellets and flakes can be found, specially designed for cichlids.

If you are going to use processed foods, occasionally pick some additional frozen/live foods to be added to the tank – this will help give them a range of nutrients. 

Bloodworms and brine-shrimps are popular options. Herbivorous foods are mostly discarded, which is why you can keep plants in the tank with a low risk of eating them. 

Feed your adults once or twice daily. Add a quantity that they can finish in just two minutes. To help them grow, juveniles should be fed slightly more often, 2-3 times a day.


Here is the scientific classification of Jack Dempsey fish

Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Cichliformes
Family: Cichlidae
Genus: Rocio
R. octofasciata
Binomial name
Rocio octofasciata

Care guide

Jack Dempsey fish has simple demands on care. The problems start with keeping a group or mixing them up with other species. 

If you haven’t kept aggressive cichlids beforehand, handling their aggression can be difficult. If your Jack Dempseys is poorly cared for, they will start harassing each other and other species. 

That species is not the best fish keeping option for newcomers. If the aggression is handled correctly, keeping them healthy isn’t difficult.

Like all other freshwater fish, they can get illnesses though. One of the most common problems is Ich (white spot disease)-an ectoparasite that appears on the body and fins as white nodules.

Raising your tank’s water temperature to 86 ° F can help treat the illness. 

Head and Lateral Line Erosion (HLLE) is another common illness. This forms on the head pits, or cavities. It’s usually caused by poor nutrition so if you spot it, you’ll need to change your diet. 

In general, an unhealthy environment promotes disease so you need to keep the tank clean. Anything that you add to an established tank can bring with it disease so quarantining things are a must.

Breeding process with Jack Dempsey

A pair of Jack Dempsey fish will darken when they are ready to match their colors. If the male is ready for mating but the female isn’t, she may be harassed to death. 

Conditions need to be close to perfect for initiating spawning. The water has to be clean, and within the parameters described above. A great trigger is a temperature at the higher end of the range (~84 ° F). 

Larger males will seduce a female more successfully (this is common for many cichlids). Once mating has occurred it is possible to produce up to 500 eggs.

The eggs are attached to a flat surface nearby such as the aquarium’s decorations, substratum, or walls. They should have hatched after three days.

The parents are quite attentive to the fry, they dig holes in the substrate in order to protect the fry until they swim freely.

Both mother and father share a duty to guard the youth. They crush even food and release it for the young to eat until they are big enough to find their own food. 

If the parents are stressed by poor environmental conditions, they may begin eating the young and need separation.

Jack Dempseys lay their eggs, such as rocks, logs or the glass bottom of an aquarium, on a flat hard surface inside their territory.

They exhibit substantial parental care like most cichlids: both parents help incubate the eggs and guard the fry when they hatch.

Jack Dempseys are known to be caring parents, pre-chewing food for their offspring to feed.

However, eating their fry is not uncommon for them when the breeding pair is overly disturbed or when something is wrong in their surroundings.


The fish is native to Mexico and Honduras, where it is found in slow-moving waters such as swampy areas with warm, turbid water, weedy, mud- and sand-bottomed canals, drainage ditches, and rivers.

It is also established in Australia, the United States, and Thailand as an introduced species (presumably as an aquarium escapee) which is locally known as the Mexican Blue Frontosa.

How big do Jack Dempsey fish get?

Usually, The Jack Dempsey fish can reach a length of up to 10-15 inches.


The coloration changes as the fish matures from a light gray or tan with light turquoise flecks to a dark purple-gray with very bright, iridescent flecks of blue, green and gold.

Their colors, under stress, change. The mature male dorsal and anal fins have long, pointy tips. These exaggerated tips are lacking in females.

Both genders significantly darken in color during breeding, appearing almost black with little to no metallic coloring. 

Various color variations are also available on the market for aquariums. Color variants include Gold, Electric Blue and Pink (a fish displaying both gold and blue characteristics)

In the aquarium

Because of its striking appearance and personal mannerisms, the fish is a popular aquarium fish. Like most cichlids, it is considered “aggressive,” but can get along in a well-populated tank, tending to be more territorial if kept with just a few other fish, thus allowing a “territory” in the tank to be easily established and defended.

Often, Jack Dempsey cichlids may appear shy, hiding in cave work. The Jack Dempsey cichlid should be provided with plenty of places to hide.

They will often first claim a cave and be very aggressive towards other tank mates who are swimming near their homes.


Every aquarium is different but most of the established tanks will not be able to create a house for a new Jack Dempseys group. This cichlid needs to have a tank specifically designed for them. 

This is mainly due to their aggressive nature, and the restriction on tank mate that this creates. It’s not a fussy species so they’re relatively easy to provide for as far as setting up the tank goes. 

Nor are they fussy about their diet, and will accept most of the same foods as other carnivorous cichlids. 

Beginners may struggle to keep those fish, but you’ll be left with some colorful fish with big personalities if you manage to.

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1 thought on “Jack Dempsey fish: Care, lifespan, breeding and tank mates”

  1. One of the only fish that I had a mated pair of. The father ate the children the first time they mated. The second time I separated father and the mother ate the children. It was kind of a horrible experience. After the fourth time the mother committed suicide by pinning herself under a tank addition. They truly were beautiful. but damn really!!?!??

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