Jack Dempsey Fish – All you need to know about this Cichlid

Jack Dempsey Fish

Jack Dempsey Fish is also known as Cichlasoma biocellatum Regan 1909, octofasciatum (Regan 1903), and nicknamed Manassa Mauler.

It is one of the most popular freshwater aquarium fishes. They are known for their fierce looks, vibrant colors, and great personalities. Although they are native to the rivers of Mexico, Guatemala, Belize, and Honduras, you can find their population well across North America, Australia, and parts of Asia.

This Cichlid receives its common name to the likeness of legendary boxer Jack Dempsy from 1919 to 1926. Jack Dempsy was famous for his merciless and aggressive attack in the ring. Despite, their aggressive nature they are popular amongst aquarium enthusiasts for their bright colors and impregnable personalities.

Before deciding on whether this fish is appropriate for your aquarium or not, you need to understand about this fish, its behavior and temperament, what do they need to thrive, and most of all how much dent does it make into your pocket. 

Let us study more about Jack Dempsey Fish/Jack Dempsey Cichlids!

Jack Dempsey Fish – an Overview

Description Category
Family Cichlidae
Type Freshwater Fish
Color Form Black, Blue, Clear, Green, Tan
Temperament Aggressive
Max. Size 10-15 inches (25 – 38 cms)
Lifespan up to 15 years
Diet Carnivores
Minimum Tank Size 55 gallon for every Cichlid
Water Parameters Acidity: 6 to 8pH
Hardness: 4-15 dGH
carbonates and bicarbonates 4-6 dGH
Temperature: 72°-86°F (22°-30°C)
Ammonia & Nitrite: 0
Nitrate: <40 ppm

Species Summary

Jack Dempsey Fish – Rocio Octofasciata is its scientific name; a species belongs to the Cichlidae Family, of over 1500 species that includes angelfish. They are native to the South Mexico rivers, Honduras, Belize, and Guatemala rivers. 

Jack Dempsey Cichlids are known to thrive in a diverse environment, where other tropical fishes could not survive. They inhabit slow-moving, shallow waters, swampy, murky, muddy, and sandy waters. They are also known to inhabit bogs and irrigation ditches and tend to live around rocks, submerged woods, and weedy zones.

Jack Dempsey is a boisterous and gorgeous-looking fish that are favorite to the most passionate aquarists.

Jack Dempsey Fish Life Span and Physical Characteristics:

Jack Dempsey Fish Size

They are beefy, compact oval-shaped fish. They have pointed anal and dorsal fins.
Jack Dempsey Cichlids comes in a range of colors; the most popular ones are blues, pinks, and golds. Their base range from dusky to dark is nearly black.
The color changes as they grow older from a pale tan with indistinct flecks of aquamarine to dark and bright purplish-grey, sparkling green, blue, and golden flecks.
The anals and dorsal fins of matured males are long and pointy, whereas females of the species have less prominent dorsal fins. The dorsal fins are in red. They have light blue lips.
However, during breeding, both males and females of the species will darken as much as black with less distinct metallic coloration.
There is a popular variety called Electric Blue Jack Dempsey fish; they are slightly smaller and less aggressive than the others. These types are possibly modified forms of wild Jack Dempsey Cichlids through selective breedings. They seem to have much bigger specks of scintillating green, blue and golden flecks when in comparison to the wild varieties.
A full-grown adult Jack Dempsey Fish is a picturesque site. In the wild, Jack Dempsey grows up to 15″ (38 cms) long. However, no breed in captivity can grow as big as or as long as they do in the wild. Yet, it can grow up to 12″ (30cms) long in a tank if you take care to recreate its natural habitat and give them enough space in your aquarium.
Jack Dempsey Cichlids’ life spans up to 15 years.

Electric Blue Jack Dempsey Fish:

Electric Blue Jack Dempsey

Recently, Electric Blue Jack Dempsey Fish, shortly known as EBD has become quite popular, especially on the internet, partly the aquarium market promoting as a variant to original species of Central and South American river Jack Dempsey Cichlids.

The origin of this species is debatable, some claim the morph has occurred naturally in the wild, whereas, others claim Electric Blue Dempsey is a cross between the original Jack Dempsey Fish with another Cichlid.

All said and done they are stunners; they have a charm of the original Jack Dempsey Fish along with long flowing fins, which is quite a common trait with Aquarium Market Bred Fishes.

Electric Blue Dempsey Fish are smaller and reportedly less aggressive than their original counterparts. 

Even as a baby it has a striking electric blue to grey and exhibits iridescent blue and green flecks just the same as its original counterparts.

Although they are less aggressive than their original counterparts, nevertheless, they are territorial and aggressive enough. 

For Feeding, Breeding, Tank size, and conditions follow the same care as Jack Dempsey Fish.

Jack Dempsey Fish Tank Size:

Jack Dempsey Fish often sold as an infant measuring only 2 to 3 inches (6 to 8 cms) and kept in a display tank together. Neophyte aquarists will not be able to imagine the size of these fishes when they grow up to adults. The male of the species can grow up to 15 inches and the females slightly shorter in length. 

You need to consider a minimum of 55-gallon tank (210 liters)for every Jack Dempsey Fish. A 100-gallon tank (380 liters) could house a pair of this species.

Tank Conditions:

There are many more parameters and equipment to think of when you are bringing one or more Cichlids to your aquarium and keeping them healthy and thriving.

Water Filtration:

Filtration is one of the important parts of any aquarium. When it comes down to this large cichlid like Jack Dempsey Fish is twice as important.
Fish constantly produce biological waste into their environment. Jack Dempsey’s waste is quite large and visible. All that waste sinks to the bottom of the tank and starts decomposing. This process produces a byproduct called ammonia. Ammonia is toxic to all the fishes.
Experienced aquarists, habitually choose a large filter, like a canister filter with multiple cylinders, when they consider bringing a large fish like Jack Dempsey for their aquarium.
These filter cartridges house many beneficial enzymes, that will digest the ammonia and convert it into a byproduct called nitrite (a toxic byproduct), and then nitrate. This process is called the nitrogen cycle.
Nitrate is a lesser-known toxic amongst ammonia, nitrite. Nitrate is colorless and odorless; the only way to detect is to measure with ion-specified electrodes (ISE). Algae bloom usually is an indication of high nitrate levels; algae start to grow with a nitrate level of 10 ppm. The maximum limit for nitrates in the freshwater aquarium is 50 ppm. According to Tropical Fish Magazine, most fish don’t show any sign of nitrate poisoning until it reaches the level of 100 ppm.
Algae bloom can lead to drowning or suffocation of your fish to death. Therefore, cleaning the filtration tank periodically is a part of the process of maintaining your aquarium clean and sparkling.
It is recommended by experienced aquarists to choose an oversized filter with a large cichlid like Jack Dempsey Fish. There is no need for air or water pump since Jack Dempsey Fish lives in slow-moving water. So, it becomes doubly important to run the filtration system to maintain a required level of Dissolved Oxygen in the water. 

Water Parameters and Conditions:

Although Jack Dempsey Fish can thrive in a wide range of water conditions, their native waterways of the South Mexican rivers, Belize, and Honduras rivers are soft and little on the acidic side. 

For Jack Dempsey Cichlids to grow to their fullest potential and to live to their maximum lifespan, it would be advisable to replicate their native habitat. The water pH level can be between 6 to 8. Even though they can live in a wide range of temperature variations 72°-86°F (22°-30°C), it is advisable to maintain the temperature around 80°F (26°C) to keep their temperament under control. 

The water hardness can be between 4-15 dGH and carbonates and bicarbonates (KH) measures can be 4-6 dGH; higher KH prevents large pH swings in your tank over time.

The levels of Ammonia and Nitrite should be 0, as minimum exposure to these toxic substances can stress your fish. Long-term exposure to Ammonia and Nitrite can make the fish vulnerable to many diseases.


Jack Dempsey Cichlids have a natural tendency to dig. If you have a substrate made of green matter and soil, they would destroy it in no time. Experienced aquarists recommend sand or gravel substrates. The sand can settle and level itself after sifting. The gravel forms small mounds and basins after sifting, which can add a character to your aquarium.  

The Cichlids change their colors to match the background. If you would like to see deep dark colors, then use a dark substrate. The iridescent green, blue, golden specks turn even more strikingly beautiful.

Your Jack Dempsey Fish will appreciate some rocks with fissures and driftwood with branches that provide a good hideout and also can use to establish their territories.

Live plants like a Java Moss, Java Fern, Anubias, hornworts, pennyworts, or water lettuce can be grown in a tank with Cichlids. Vallisneria, commonly known as eelgrass, tape grass, or Vallis provides a dense cover for the fish to explore.


Proper lighting is important to bring out the colors of your Jack Dempsey Cichlids. Fluorescent aquarium bulbs are common as they highlight artificial colors of aquarium substrate, plastic plants, and ornaments. However, the natural iridescent colors of Jack Dempsey Fish get lost in this artificial light. Moreover, the bulbs need replacements to maintain the same level of illumination. 

Some of the experienced aquarists recommend LED lighting fixtures. They are durable and uses much less energy. Some LEDs allow you to customize the light colors to highlight the fish colors.

Lighting is purely aesthetical as long as you recreate the slow-moving murky water dim light in the aquarium tank where Jack Dempsey Fish lives.

Temperament and Behaviour:

This Central and South American Cichlid receives its common name to the likeness of legendary boxer Jack Dempsy from the ’20s. So, you don’t imagine seeing even for a moment any docile behavior. The novice aquarists and those who have used to keeping peaceful and docile fish such as Ember TetraNeon Tetra, Rainbowfish, White Cloud Mountain minnows, Guppies, Endler’s livebearers, Harlequin Rasbora, Corydoras catfish, etc. will have quite a difficult time with your gorgeous and powerful Jack Dempsey Fish.

Jack Dempsey Cichlids quite often seem shy and hideaway in their cave work. In habitat, they quickly claim a cave-like spot and will be aggressive to other fishes that tread near its territory just like a dog being aggressive to other dogs that pass by their homes.

They stay and swim mostly in the middle and lower levels.

If you are planning to get more than one Jack Dempsey, it is better to keep them in a species-specific tank. A small or a large group of fishes are easier to manage and look after rather than a pair. Jack Dempsey pairs tend to become doubly territorial and exhibit aggressive behavior.

While having Jack Dempsey species-specific tank one major point to consider is that not to keep 2 male Jack Dempseys in the same tank.

Jack Dempsey Fish Tank Mates:

Jack Dempsey Fish Tank Mates

Although like most Cichlids, Jack Dempsey is territorial and aggressive, they can make out in a well-populated aquarium tank.  Jack Dempsey Fishes are prone to more territorial and aggressive in pairs.
In general, you need to choose a similar size and with similar temperament fishes as their mates. Each one should be able to defend themselves.
The best mates can be of the other Central and South American Cichlids like Salvini, Firemouths, Nicaraguan, Pleco, green terrors, and Convicts. However, avoid their African counterparts as they are way more aggressive than the Central, South American Cichlids.

Jack Dempsey Fish Food:

Jack Dempseys are fundamentally carnivores. In the wild, they hunt on crustaceans, insects, and other small fish.
They are not choosy when it comes to the diet. You can feed them brine shrimps, worms like bloodworms, blackworms, daphnia, some large insects like crickets, grasshoppers, and some dried pellets, flakes, etc.


Jack Dempsey Fish is one of the is easiest to spawn amongst the  Cichlids. Experienced aquarists suggest it would be best to bring a male and a female that have grown up together in a separate tank. This achieves compatibility and reduces the friction between them during their courtship.
The temperature of the water needs to be on the higher side of 79-84°F (26-29°C) with a neutral pH.
Dempsey female lays up to 500 eggs on a flat rock or any flat surface. It takes 3 days for the eggs to hatch; once hatched the parents collect the fry and keep them in a burrow in the substrate. The parents are protective of their fry and they chew the food and release it for their young. However, if the parents are stressed they might eat their young and it is advisable to separate them from the young.
How to care for Jack Dempsey Cichlids

Disease and care:

Jack Dempsey Cichlid Care

Like most of the freshwater fishes, they are susceptible to infection and diseases. Ich is one disease that they often get. Increasing temperature up to 86° F (30° C) for a few days can heal the Ich.

Poor water conditions and nutritional deficiency of vitamin C, vitamin D, Calcium, Phosphorus can cause discus, “a hole in the head”.  

To avoid “a hole in the head” disease all you need to do is to take care of the water parameters, clean the filter regularly, and feed them a balanced diet. 

They are also prone to bacterial and fungal infections, parasitic infestations, etc. just like most freshwater fishes. 

Prevention is better than cure:

  • Use a slightly larger size filter than the one recommended to you.
  • Clean the filters regularly.
  • Check the water parameters weekly once and adjust them
  • Make sure to feed them with a balanced diet
  • Take good care while introducing a new fish into the tank
  • Take the utmost care with substrates, plants, and other decoratives.

Is Jack Dempsey Fish right for you? A Summary:

All the aquarists who have kept Jack Dempsey Fish have one thing common to say about whether experienced or inexperienced aquarium keepers is that it is rewarding. They all swear by that they can’t think of having any other fish after Jack Dempsey Fish. 

The Aquarists are deeply enchanted by its fierce look and the personality and how they take to the hands that feed them.

Having a Jack Dempsey Fish is like a pet, just the same as having dogs or cats. 

One another observation newbie aquarists share is that they are shocked to see its slow growth (a couple of months); Do not forget the fact that with the right care and environment their life spans up to 15 years.

If your purse is thick, don’t mind denting it a bit and you like a colorful fish with a strong personality, Jack Dempsey is the Fish for you.

1 thoughts on “Jack Dempsey Fish – All you need to know about this Cichlid

Leave a Reply

Your email address will not be published. Required fields are marked *