Jack Dempsey Fish: The Full Care Guide

JACK DEMPSEY CICHLID; The complete care guide

It’s hard to be a fish hobbyists and not know of the popular cichlid family, and in terms of them, the Jack Dempsey can not be missed.

These fish has contributed a lot to the family’s popularity, perhaps more than cichlids like Rainbow, Bolivian Ram and Blue Acara despite its ferocious personality.

In my opinion, they make up for that aggression with their interesting personality and colorfulness

Regardless, some hobbyists prefer keeping species that will offer some interesting challenges to spice up the passion.

If that’s you, Jack Dempsey is one of the finest choices. I definitely prefer them to the infamous Wolf Cichlid or the Red Devil Cichlid- these two are so darn aggressive to be enjoyed by most hobbyists.

Bear with me as you go through this guide that lays out all you need to successfully care for the Jack Dempsey fish from tank size, water parameters, food and diet, tank mates, common diseases and much more.

After reading you be able to decide whether to give this fish a shot or not.

Jack Dempsey has proven to have the capability of thriving in different environments that many other tropical fish could not. 

The original Jack Dempsey which is now under the name “Rocio octofasciata” inhabits the Papaloapan River Mexico, Yucatan, Guatemala and the Ulua River Honduras.

They are normally found in shallow waters, slow-moving streams, swampy areas and irrigation ditches. They prefer living in weedy areas with either sandy or muddy bottoms.

When in rivers, they stick to areas with low water velocities like near rocks, tree branches and natural caves. They can survive areas with hot water and reduced oxygen level, so it’s hard to disagree with the Jack Dempsey incredible hardiness. 

In recent years, non-native population of Jack Dempsey was discovered by biologists mostly around tropical fish farms in Florida. It’s logical to assume that they were runaways from the nearby farms. 

It’s interesting to learn that these fish have also been located in different dispersed locations which include Hawaii, Thailand, South Dakota, Australia and Connecticut.

Specimens found in these locations are believed to have been introduced by fish hobbyists who probably couldn’t handle, or didn’t need the fish anymore. 

Jack Dempsey Care Snippet

  • Maximum fish size: 15.0 inch
  • Minimum tank size:55 gallons
  • Aquarist Experience Level: Intermediate – Expert
  • Temperament: Very Aggressive and Territorial
  • Temperature: 72°F to 86°F
  • PH: 6.0 to 7.0
  • Hardness: 9-20dGH
  • Diet: Omnivore
  • Care Level: Relatively easy
  • Ideal tank mates: Green Terror, Silver Dollar, Firemouth Cichlid Plecos, Giant Danio, Rainbowfish, Loaches, et Cetra


Jack Dempsey has an assertive facial appearance. One look at them would tell you this fish won’t kid around. Their body shape is similar to lots of other cichlids. It’s also common among many predatory fish species.

They have an oval-shaped body with long fins. When looking at them face to face, they appear compressed.

Thanks to the compressed muscular body, they are hard to spot by prey and can move swiftly. This is why they are able to surprise and whack down an unsuspecting prey in no time. 

Jack Dempsey body color changes as they grow and varies from individual to individual but the most popular ones are blue, pink and gold. 

As Juveniles, they tend to exhibit light grey hue with light vertical stripes. The stripes fade as the fish matures. 

As they start to mature their real fascinating color start to emerge. They have a dark blue hue as the background color. A colorful green and blue patches start from the gill cover to the tail creating a beautiful pattern along the side of the fish. 

The edge of their dorsal fin is are covered in red. They have a highly pronounced light blue colored lips which help make the face bolder.

Matured Jack Dempsey

There are some differences between male and female Jack Dempsey and the differences go like this;

  • Females jack Dempsey are smaller than the males
  • Females tend to have lighter body coloration 
  • Females have shorter and less pronounced fins than males

Jack Dempsey color is known to change temporarily in two scenarios which are; during mating and when stressed. They turn darker during mating, when stressed they turn lighter. 

There is a very popular and awesome variety of the Jack Dempsey known as the Electric Blue Jack Dempsey. It’s preferred by many hobbyists because it is less aggressive and slightly smaller than the actual one. 

What’s more, is that it has a captivating electric blue color as the name suggest and due to that it can stand out in virtually any type of aquarium.

There are two variations in opinion regarding the origin of the Electric Blue Jack Dempsey. Some argued that it’s a selective cross-breeding of the wild types while others argued that it came to be as a result of mutation.

Electric Blue Jack Dempsey

Jack Dempsey Size

Majority of Jack Dempsey are sold when Juveniles. At this time they are  usually about 2 to 3 inches in size. 

However, in a tank with adequate space and proper conditions, a male Jack Dempsey can grow to a maximum size of about 10 inches long and the female can grow to about 8 inches long.

In the wild, they grow a bit bigger with male growing up to 12 inches long and female growing up to 10 inches long.


Jack Dempsey is one of those species with a very long lifespan. Unlike popular species such as Guppies, Platy, Bettas, Gouramis which all hardly make it past five years, Jack Dempsey can live for 10-15 years.  

This is important to know because it tells you that you will be in a long term commitment should you choose to bring one home.

Just like it is with any aquarium fish, ideal water conditions is very crucial in prolonging their lifespan.

Temperament and General Behavior

Part of the reason this fish was given the name “Jack Dempsey” is its aggressive nature similar to that of the famous 1919 Heavyweight Boxing champion of the world “Jack Dempsey”.

At the time it was introduced in the aquarium space, it was as considered as an extremely aggressive fish. 

But today, there are cichlids are way more ferocious than the Jack Dempsey such as the wolf cichlid or the Red devil cichlids. Compared to these two, Jack Dempsey is a manageable fish aggression wise.

That said, these fish is still not a good choice for beginners who do not have experience in dealing with aggressive species.

Keeping it successfully will require an experienced aquarist. Note that this has nothing to do with the difficulty in its water requirements and feeding, it’s just about the aggression.

Jack Dempsey is also quite territorial, especially towards their kind and other similar looking species.

You may think they are not as aggressive and territorial as talked about when you bought a juvenile at a pet store. But the thing is, the aggression starts to build up and increases as they grow.

As such, they can only live together without a major problem in a tank equipped with crevices, caves where each fish can establish its territory. 

Jack Dempsey Tank size and Requirements

Simply considering the Jack Dempsey size, territorial nature and the amount of waste a fish this size will put out, will hint you that they will need more than your 10 or 20 gallons tank. 

For those reasons, the recommended minimum tank size for keeping a single Jack Dempsey is 55 gallons

This will provide it with adequate space to roam about and explore different sections of the tank. It will also allow you to install the recommended tank decorations.

If you have 2 or 3 of them, you will need an aquarium that is at least 150 gallons to be on the safe side.

After you select the appropriately sized tank, what remains is fitting and equipping it with all it requires to make the fish adapt easier and live at its best.

This entails filtration, aquascaping, heating, lighting, substrate and tank decoration.

Rocio Octofasciata


Filtration is not something you would want to skimp on regarding your tank. It’s even more crucial if you a dealing with a fish like the Jack Dempsey which put out way more waste than tropical nano fish.

It’s obviously due to their size and as such, its only logical if you set up the tank with an equally large and powerful aquarium filter. 

Considering the tank handling capacity of aquarium filters are usually exaggerated, its best to get the next bigger filter.

Meaning, if it’s stated that a filter can handle a 150-gallon tank its best to buy one that can handle more a 150 gallon for your 150-gallon tank.

You can make use of popular options like the hang-on-back (HOB) power filter or a canister filter. Make sure you maintain the filter as recommended to make sure it’s doing its function efficiently.

Bear in mind that dirty water will temper with the nitrogen cycle of the tank which can have a serious repercussion on your fish. 


Jack Dempsey will need a heater seeing as they originated from Mexico where temperature can reach up to 90°F

Its recommended you make use of a heater that will not struggle in keeping the water warmly sufficient. 


Despite their toughness, Jack Dempsey are often timid. This is why it’s not a good idea to use very bright lights as that can force them go in to hiding.

If your light is considerably bright, ensure you have some floating plants that will create convenient shades. 

Use an efficient LED aquarium light as opposed to the commonly used fluorescent lighting to bring out the natural color of the fish.

Aquascaping for Jack Dempsey

When dealing with Jack Dempsey, it better to make use of floating plants. These fish together with many other cichlids, are unrelenting tank diggers.

They dig when searching for food and sometimes just for the fun of it. They also like messing with things like the plants in the substrate.

For these reasons, anything attached to the substrate is very vulnerable.

I recommended you make use of easy-care floating plants such as Hornwort, Frogbit, Java Moss, or Water Lettuce.  If you want planted plants your best bet is to use resilient live plants such as Anubias or Java Moss. 

If you use something planted it is almost certain that they will rip it out when they are reorganizing the tank.


In light of the Jack Dempsey digging habit, the best substrate to make use of in their tank is sand. The advantage of using sand is that it is easier for them to dig out and can settle back and level itself after they are done. 

Large gravels substrate, on the other hand, will be harder for them to shift and will lead to a mess of formed piles and craters all over your aquarium. 

Tank decoration

Jack Dempsey can not survive in a bare tank with no provision for areas they can hide in and establish their territory. 

Even if you keeping only one fish, you will still need to make provision for that. It only becomes more important if have more than one. 

Equip the tank with elements such as branches, driftwoods, pieces of rocks and introduce several caves throughout the tank. This will result in a very nice habit that they will love. 

The better you decorate and equip the tank the easier they will adapt and the less headache you will have when introducing additional tank mate. 

Water Parameters

Jack Dempsey can tolerate a wide range of water conditions. It pays to provide tank conditions that closely resemble those of the fish habitat.

Using this, it has been established that Jack Dempsey need water with a temperature of range of 72 to 86°F, a pH of between 6 to 8 and a water hardness of between 9 to 20dGH.

It was pointed out by some aquarists that warmer temperature sometimes tends to increase the fish aggression and it best to keep the water with a maximum temperature of about 78°F.

It would be beneficial to test out yours and see if that’s the case and act accordingly. 

Jack Dempsey Food and Diet

Jack Dempsey are carnivorous fish that will gobble any animal they can fit in their mouth. Small fish, crustaceans, worms and insects are what make the majority of their food in the wild.

When you consider their size, it’s a good thing that in captivity they readily consume all sorts of carnivorous fish food together with flakes and pellets. 

You have lots of options on what to feed them from live, prepared, fresh and frozen food. 

They are mostly fed processed pellets and flakes because of their availability and inexpensiveness. 

It’s highly required you offer them varied diets to make sure they get the required nutrients their body needs.

You can supplement the diet by offering delicacies such as bloodworms, brine shrimp, fresh shrimp, crickets and so on. 

Its recommended you feed them in 2 minutes, 1 to 2 times a day. Young ones should be fed 2 to 3 times a day for the same 2 minutes as well. 


Fortunately, Jack Dempsey is relatively easy to breed. As a way of easing the process, it has been advised by expert breeders to combine the fish right from when they are small. 

That way, a pair will separate from the group and this will assure compatibility and lower the possibility of fighting during courtship.

It’s a good idea to remove other fish from the aquarium before the courtship to prevent them from getting bullied or even killed.

Jack Dempsey color will darken when they are ready to mate. This is important to notice because if the male is ready to mate and the female is not, he may continue to bully her to the point of death.

Be watchful and make sure to remove her if things get intense. You can reintroduce her back to the tank when she is ready to spawn. 

Make sure to include a flat stone in the tank, that will serve as a base for the eggs. After the mating has occurred, which can give raise to up to 500 eggs, the male will then fertilize them.

Contrary to most aquarium fish, cichlids have parental instincts. They care and protect both their eggs and fry. 

Due to this, the parents jack Dempsey will watch over the eggs. After it hatches in around 3 days, they will dig in the aquarium substrate and deposit them in the pits.

The fry will start to swim in around 10 days. The parents will keep watching and helping the fry until they are matured enough to find themselves food.

Jack Dempsey Tankmates

Large size plus aggressive and territorial behavior has made Jack Dempsey tank mates options quite limiting. These fish is not a good choice for community tanks. 

Size, temperament and water condition are what we consider in choosing a good tank mate for an aquarium fish. 

Size-wise Jack Dempsey is one of the largest aquarium fish and is capable of making a snack out of all nano fish species. 

That means keeping them with Tetras, Rasboras, Bettas, Fancy Guppies, Endlers Livebearers, Pygmy Cory, Galaxy Rasbora, sparkling Gourami, Least Killifish to mention a few, is out of the question.

Aquarium critters such as shrimps are known to get eaten unless they are well matured. The rule is; don’t keep them with any species small enough to fit in their mouth even if other parameters check out.

Aggression is also important factor to consider. This is because some fish may be too big to get eaten by the Jack Dempsey but if they have a very calm and reserved they can get bullied to death by this fish. 

Something to point out is, do not combine them with species that are more aggressive than they are such as the Wolf Cichlid, the Red Devil cichlid or the Black Nasty Cichlid. That toughness and dominance work both ways.

Logically, its best to keep Jack Dempsey with species of similar size and aggression levels such as Firemouth CichlidGreen Terror Cichlid and Severums Cichlids. 

Other species such as Oscar, Birchir, Blue Acara, Angelfish, silver dollars and Plecostomus have been proven to work well as Jack Dempsey tank mates.

Having said that, you will still need to provide a very large tank with abundant caves and crevices to successfully keep them with other tank mates.

If you have the interest of adding other fish to your tank, it may be best to add more Jack Dempsey before considering other fish.

That’s not to say they will get along peacefully with each other. It’s just that they will be easier to handle provided you have the proper tank set up. 

One thing to point out is that refrain from keeping 2 matured males together because they will continue to fight each other until one or both are dead.

It’s better you keep three upward. That way, the dominant one will not be fighting only one fish and the attacks will be lessened.  

You can keep 2 mating pairs, they will fight occasionally and other times they will get along peacefully.

Common Diseases

Ich and other diseases that affect freshwater fish such as bacterial infection, fungal infections, parasitic infection and skin flukes are known to affect Jack Dempsey.

The easiest and recommended way to cure an inch is increasing the water temperature to about 86°F for a few days. The nice thing is that these fish can tolerate that kind of temperature.

There is another well know disease that afflicts them which also affects Discus. Its referred to as head and lateral line erosion. It’s symptoms are the formations of cavities on heads and face.

This disease is considered to be caused by nutritional deficiencies. 

To lower the chance of your Jack Dempsey getting sick you must take good care of their water. This can be achieved by monitoring the water parameters routinely to make sure they are within the desired ranges.

You also need to replace 20% of the water every 2 weeks and make sure to use a high-quality and appropriately sized filtration system.

Next is, feed them nutritious food as recommended earlier. 

Lastly, make sure that any fish you are to add to the aquarium is disease-free. You can achieve that by quarantining any fish you bring for some days to make sure it’s alright.

Its worth remembering that diseases are more treatable at an early stage. Therefore, it pays to develop the habit of observing your fish activity occasionally.

This can help you become familiar with the pattern of their activity so you can easily identify a problem.


Keeping a jack Dempsey will require you provide an adequately sized aquarium equipped with all the elements they require in a tank. If you want to have more than one, the decorations become even more important.

They need a large and efficient water filter to handle their enormous waste. Their diet also need to be diversified so that they can have all the nutrients their large body requires.

Only tank mates with similar size and temperament can live together with them successfully.

Additional measures need to be taken during their spawning to make sure no fish lose their life.

They are vulnerable to a few diseases which could be averted with proper water quality and diet. 

This pretty much sums up the Jack Dempsey care and if you can adhere to these requirements you can give them a shot.

I hope this guide has cleared everything for you regarding keeping the jack Dempsey and if you are deciding whether to keep it or not I hope it helps you make the right choice.

Please feel free to rich out if you have any question we haven’t covered or if you have any info you think will help improve this guide. We’ll be more than happy if you do

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