What Kind Of Fish Is A Jack Dempsey?

What Kind Of Fish Is A Jack Dempsey? Jack Dempsey Fish Cichlids are a common sight in tropical aquariums. They come in all shapes and sizes, each with its own behaviors and personality.

Jack Dempsey Cichlids are archetypal cichlids popular for so long that their namesake, the famed American heavyweight boxing champion of the world, William “Jack Dempsey” Harrison, had his heyday in the 1920s!

Jack Dempseys are one of the most well-known cichlids. Dempsey remains ranked number seven in the Top 100 greatest punchers of all time and for fishkeeping pioneers, this Central American cichlid must have had many similarities.

However, compared to some cichlids now commonly available, the Jack Dempsey fish has dropped down the rankings and is kept now more for its color than ferocious behavior.

They are infamous for their aggression and don’t play well with others, but that does not mean 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 that don’t will struggle to stop them from harassing their tank mates. When kept properly, this carnivorous fish introduces various colors and plenty of activity to your tank.

Keeping Jack Dempsey Cichlids in The Aquarium

This article will help you get to grips with Jack Dempsey Fish, covering their ideal tank setup, feeding preferences, tank mates, and much more…

Care Level:Intermediate
Color Form:Gray with bright flecks
Jack Dempsey Lifespan:8-10 Years
Size:10-15 Inches
Minimum Tank Size:80 Gallons
Tank Set-Up:Tropical freshwater
Compatibility:Aggressive fish of a similar size

Rocio octofasciata or Jack Dempsey are fish from the Cichlidae family.

The Jack Dempsey naturally occurs in Mexico, Honduras, Guatemala, and Belize, although it has been introduced — or escaped — to other areas with year-round warm climates. It naturally inhabits warm, sluggish waters, feeding on worms, crustaceans, insects, and fish.

Most cichlids are either from Africa or America. Jack Dempseys are no exception and are found in slow-moving waters across North and Central America, such as Mexico and Honduras. Cichlids have diversified rapidly in these areas.

Like many cichlids the Jack Dempsey Fish has an interesting past; starting off as Cichlasoma biocellatum more than 100 years ago, then changing to Cichlasoma octofasciatum, Heros octofaciatus, Parapetenia octofasciata, Rocio octofasciata, Nandopsis octofasciata, and Archocentrus octofasciatus.

However, despite these many changes, the species will rarely be mistaken for anything else. I’ve kept them many times because ‘JDs’ are hardy, easy to keep, easy to breed, colorful, cheap to buy, and improved with age.

They have now been established in the warm waters of Australia and Thailand, where it’s known locally as the Mexican Blue Frontosa.

Jack Dempsey Fish Lifespan

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

Jack Dempsey Fish Price

It might be a little harder to find a particular color if you have a specific variety in mind.

Most pet stores sell Jack Dempsey Fish for $5 – $10 – rarer varieties can cost a bit more though.

Typical Behavior

Is Jack Dempsey aggressive?

Remember these fish are aggressive and need their own territory. So give them each a spot to hide away.

Many people are put off by the aggressive nature of this species. Those not used to keeping aggressive fish might struggle to care for them properly, so they are not recommended for beginners.

Can You Keep Two of Jack Dempsey’s Together?

They tend to be less aggressive in well-populated tanks because it’s harder for them to single out and pick on stray fish.

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

They spend a lot of time hiding away in these caves so can appear quite shy. Mostly they will stay in the middle and lower levels of the tank.

The Appearance of Jack Dempsey Fish

What Kind Of Fish Is A Jack Dempsey?

What Kind Of Fish Is A Jack Dempsey? Their common name is based on their appearance. They have strong facial features and aggressive nature, similar to that of the 1920s boxer Jack Dempsey.

This species has a large oval body, with long fins. Males will be larger with longer fins.

Jack Dempsey Fish Size: How big do Jack Dempsey fish get?

The Jack Dempsey fish will grow between 10 to 15 inches, but the females grow a little shorter.

It’s quoted up to a maximum of 25cm/10”, although I’ve never seen adults that size. Much more realistic is 20cm/8”, with females less than 15cm/6”.

They are also tough, quite boisterous fish, yet not massive in size — meaning that for most, if not all, of their lives they could be housed in a 120cm/4’, or ideally 150cm/5’ tank.

I’m not recommending a 180 x 60 x 60cm/6 x 2 x 2’ tank as a minimum, as I would for other Centrals like a Midas cichlid.

Although more boisterous than your average fish, they are certainly not one-fish-one-tank creatures, so can be housed with other large, hardy species.

Jack Dempsey Fish Colour

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

The color will vary from individual to individual, especially since their color changes as they age. Older fish are a dark purple-gray with bright blue-green flecks, Younger fish become pale gray with green flecks.

Colors can change temporarily – they get pale when they are stressed and dark while mating.

You can look at their fins to sex them. Males have long dorsal and anal fins with pointed tips, and females have shorter fins that are less pronounced.

A popular blue variety of this species is available which is known simply as the electric blue Jack Dempsey. This variety is slightly smaller and less aggressive.

Buying Guide…

This depends on whether you intend to breed them. To get the best value, buy juveniles around 5-7.5cm/2-3” in length.

If you want them just for behavior, character, and color in a mixed community of cichlids and catfish, just buy one and it’ll be fine.

As with all cichlid “community” set-ups try to keep shapes and colors different, so that the fish aren’t competing like for like.

Severums make good tank mates as they are large, deep-bodied, differently colored and patterned, yet quite placid.

If you want to breed get four or five — pick those with the most contrasting size, shape, and behavior from your dealer’s tank. To sex them, males are larger with bigger heads and will dominate dealer tanks, even when small.

They become longer too, can turn a pinkish base color, especially on the gill covers, and tend to have little or no blue speckling on the lower jaw.

If you want more definite sexing, pick from fish 10cm/4” and larger. Here males have a longer head, with a more masculine jawline, and, depending on the mood, may be quite pale.

If lucky, a frisky female will show herself by turning very black and highlighting the blue speckles on her gill and jaw.

You could see some black vertical barring on her too and, when they pair, both will turn more intensely black and look even scarier and imposing — if that’s possible!

Juveniles can double in size within a year and sex out, but if you don’t want to wait adults are widely available, usually returned to shops by previous owners.

Beware of similarly looking “pairs”, as an adult pair should clearly look different, with a much smaller female and a longer, larger male with a bigger head. I’ve seen “pairs” on sale which are two males just tolerating each other and probably siblings.

To avoid inbreeding, source your male and female from different shops, from different batches, and at different times. Having said that, not buying them as a mated pair will necessitate work pairing them.

With nearly all artificially-paired, egg-depositing cichlids you add female to existing male. He sees her as a ripe female entering his territory and wants to spawn within seconds of her arrival, but she is not ripe with eggs or receptive.

The male thinks “stuff you then”, and beats her up for not clearing off — which, of course, she can’t.

You’ll observe the new pair the next day, finding the female in the top corner looking like she’s been up and down a cheese grater and close to death.

To prevent this scenario you really need a divider, to ripen the female first then introduce the male to her, and then be ready to intervene if it goes wrong. The good news is that once paired, they should be good for cohabitation forever.

Jack Dempsey Habitat and Tank Conditions

You will see Jack Dempsey fish living in a range of slow-moving freshwaters in the wild. This includes canals, murky rivers, swampy areas, and lakes.

They prefer tropical climates, so they are used to warm waters. The environment would be slightly acidic with low light levels.

Their surroundings would be a sandy, muddy substrate with rocks and debris sitting on top. Plants would be dispersed around too.

Jack Dempseys choose caves, pipes, or overhangs to spawn under, usually on the base, and they usually dig a pit around it in which to herd the fry and prevent you from viewing them.

JDs spawn readily both in your main tank and in breeding tanks, and although it is a wonderful sight I advise caution as a mated pair will spawn and spawn, and you will have real problems rehoming the fry.

Tank Setup

Starting at the bottom of the tank, pick a soft sandy substrate since Jack Dempseys spends lots of their time in the lower levels of the water.

When adding decorations, make sure you have multiple caves spread around the tank so that your fish can find and claim their own territories.

You can add plants too as they don’t usually destroy them. However, you might find that one day they decide they do not like the plants in the tank and have destroyed them. Be careful to check that any other species you keep won’t destroy them either.

They will need a heater to maintain a temperature between 72-86°F. The pH should be 6-7 and water hardness should be 9-20 dGH.

An air or water pump is not needed because they prefer slow-moving waters, you will just need a filter to create a slight current.

Avoid bright lights or your Jack Dempseys will just hide away. Their natural water would be slightly murky so use some dimmer lights. Floating plants (like hornwort) can be used to shade certain areas.

Jack Dempseys are middle to bottom dwellers and territorial, so place décor to carve up the tank bottom into clear territories, but also provide vertical structures or plastic plants to break lines of sight.

You could use tough live plants like Java fern or Anubias on wood or rocks, although when I keep JDs the fish do their own aquascaping when growing.

You’ll want décor that’s easy to maintain and keep clean too.

Jack Dempsey Fish Tank Size: What Size Aquarium Do They Need?

Keeping them in a big enough tank is important as a small tank will provoke their territorial tendencies.

Jack Dempsey fish need at least an 80-gallon tank.

How Many Can Be Kept Per Gallon?

Each fish will need at least 55 gallons of water, but they will appreciate more space.

Jack Dempsey Fish Tank Mates: What Fish Can Go With Jack Dempsey?

The aggressive nature of Jack Dempseys can be quite restrictive when looking for tank mates, but that does not mean there aren’t some good options out there.

Tankmates generally need to be a similar size with the same aggressive temperament. This means that no fish can fit in another’s mouth, and everyone can defend themselves.

Peaceful species will be harassed, possibly to the point of death. Some tiny fish such as tetras will just be assumed as food.

Oscar fish are a popular option as are Mbuna cichlids. Other choices include Angelfish, Birchir, Blue Acara, Clown loaches, Convict Cichlids, Firemouth Cichlids, Plecostomus, and Silver Dollars.

Invertebrates like shrimp and snails are popular in tropical aquariums, but they will likely be viewed as a snack.

Can You Keep Jack Dempsey Fish Together?

Keeping Jack Dempseys together in a species-only tank is the best option for beginners. It would be very tough to keep other species alive in the long run.

Just remember males don’t tolerate other males very well, so one per tank is the safest option.

Jack Dempsey Diet and Feeding: How Often Do You Feed Jack Dempsey Fish Food?

As carnivorous fish, Jack Dempsey’s diet would normally consist of anything meaty that they can fit into their mouths. They can easily grab worms, insects, crustaceans, and also little fish.

There are many options for feeding them in a home aquarium. They are not picky eaters so you can choose what is easiest for you.

Processed dried foods are generally cheaper and readily available. You can find pellets and flakes designed specifically for cichlids.

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

Popular options include bloodworms and brine shrimps. Larger insects like crickets, grasshoppers, and fruit flies will go down very well with your Jack Dempsey.

Herbivorous foods will mostly be rejected, which is why you can keep plants in the tank with a low risk of them being eaten.

Feed your adults 1-2 times a day. Add an amount that they can finish within two minutes. Juveniles should be fed a bit more often, 2-3 times a day, to help them grow.

How Do You Take Care Of A Jack Dempsey Fish In Aquarium?

Part of what has made JDs so popular is their ease of keeping.

Jack Dempseys have simple care requirements. The problems start when you keep a group or mix them with other species.

How do you take care of a Jack Dempsey fish in an aquarium?

In nature, their waters are generally hard and alkaline, pH 7-8, with a temperature range from 22-30°C/72-86°C, depending on the time of year.

That encompasses a large bracket of tolerable water conditions, matching how most of us keep our tropical tanks — and if your pH were to go higher or lower, that’s fine too.

A 240 l/ 53 gal tank with an external filter would be a good start for some juveniles. Jack Dempsey prefers to mouth the substrate looking for food. They will dig while breeding, so provides a substrate some 5cm/2” deep of grit, sand, or gravel, or a mixture of types and grain sizes.

I prefer the natural look, so decorate with large pieces of bogwood and large rocks, placing the rocks first so if the fish do dig, you won’t get rockfalls.

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

This species is not the best option for newcomers to fish keeping.

If the aggression is handled properly, it is not difficult to keep them healthy.

Just like all other freshwater fish, they can also get diseases. One of the most common issues is Ich (white spot disease) – this is an ectoparasite that appears as white nodules on the body and fins.

Raising the water temperature in your tank to 86°F can help to treat the disease.

Another common disease is Head and Lateral Line Erosion (HLLE). This form pits or cavities on the head. It is usually caused by poor nutrition, so you will need to change your diet if you spot it.

An unhealthy environment usually promotes disease, so you need to keep the tank clean. Anything you add to an established tank can bring disease with it so quarantining things is a must.

Breeding Jack Dempsey Fish

When a pair of Jack Dempseys are ready to mate their colors will darken. If the male is ready to mate but the female is not, she may be harassed to the point of death.

Conditions need to be near perfect for spawning to be initiated. The water needs to be clean and within the parameters outlined earlier. The temperature at the higher end of the range (~84°F) is a good trigger.

Larger males will be more successful in seducing a female (this is common for many cichlids).

Once mating has occurred, up to 500 eggs can be produced. The eggs are attached to a nearby flat surface such as decorations, the substrate, or the walls of the aquarium. After three days they should have hatched.

The parents are quite attentive to the fry, they dig holes in the substrate to protect the fry until they are free-swimming. Both the mother and father will share the duty of guarding the young.

They even crush up food and release it for the young to eat until they are big enough to find food themselves.

If the parents are stressed by poor environmental conditions, they might start eating the young and will need to be separated.

Are Jack Dempsey Cichlids Right For Your Aquarium?

Every aquarium is different, but most established tanks won’t be able to house a new group of Jack Dempsey. This cichlid will need a tank designed especially for them.

This is mainly due to their aggressive nature and the restriction this creates on tank mates. It is not a fussy species, so as far as setting up the tank goes, they are relatively simple to provide for.

They are also not fussy about their diet either and will accept most of the same foods as other carnivorous cichlids.

Beginners may struggle to keep these fish, but if you manage it you will be left with some colorful fish with big personalities.

Electric Blue Jack Dempsey Fish

The Internet is great for acronyms and this variety is often referred to online as the EBJD — Electric Blue Jack Dempsey.

I should love these stunning fish but, I’m quite turned off.

Part of the original species’ charm is in its subtle coloration and the challenge of conditioning it over the years to create a stunning adult. Buy a small Electric Blue Jack Dempsey Fish and it’s already bright blue.

Next is the origin. It’s the source of debate, but I feel the EBJD was created by crossing a JD parent with another, probably Central American cichlid species. Some will argue that they occurred naturally in a freak spawning and have been line-bred from that.

However, these have longer fins (a typical hybrid trait), different skull shapes within batches of juveniles — and not just the usual male and female either — and some have irregular scales.

Apart from this, despite seeing pairs of Electric Blue Jack Dempsey Fish, I have not yet seen any of them produce viable EBJD fry.

Instead, people pair them with ordinary Jack Dempsey and sell them as “blue gene Jack Dempsey” which just looks ordinary.

They are stunning fish, not deformed like Parrot cichlid hybrids but nevertheless of questionable parentage.

The price puts me off too. I first saw some on sale during a PFK shop tour at £7.50 some five-plus years ago. The most recent juveniles I noted were £42.50!

Electric Blue Jack Dempsey Fish Size

This variety of fish is a little smaller. It is closer to 8 inches (20 cm) in length, rather than a full-size Jack Dempsey Fish which is almost 10 inches (25 cm). They naturally have a life span of 10 – 15 years.


How big do Jack Dempsey fish get?

Size: Perch-like in form and shape, the Cichlasoma Octofasciatum can be described as a massive cichlid with a length of between seven and eight inches (18-20 centimeters). The name commonly is a reference to boxer Jack Dempsey, because of their savage manner of fighting. They can be very aggressive and exuberant. schools are created only when young.

What is the lifespan of a Jack Dempsey fish?

It is believed that the Jack Dempsey cichlid fish has an average life span of 10 years when kept in the home aquarium. However, providing the proper treatment and a clean environment can increase the lifespan of this fish to up to 15 years. The length of this fish is 12 inches. It should be placed in sets of 6 or more fish.

What do Jack Dempsey fish eat?

The Jack Dempsey fish are mostly carnivores. Their diet is comprised of everything that could be sucked into their mouths. This includes worms crustaceans, insects and mollusks, crayfish algae and small aerial insects, and even tiny fish.

Are Jack Dempsey fish rare?

Jack Dempsey is readily available via online retailers and fish shops. They are generally not costly fish and usually, you can buy a small specimen for less than $10. If you’re planning to include the Electric Blue Jack Dempsey in your fishing setup, be prepared to pay an extra amount because this kind of fish is very rare.

Do Jack Dempsey fish have teeth?

Jack Dempsey, cichlids do have teeth. Since they are carnivores, their teeth can be very beneficial in taking in meat. The idea of raising these fish for pets is not advised for novices. However, if they’re kept in tanks with plenty of fish they are less threatening than in the wild.

Conclusion: What Kind Of Fish Is A Jack Dempsey?

Is Electric Blue Jack Dempsey aggressive? This dazzling fish is a generally occurring variant of the Jack Dempsey Fish, which is an American cichlid. The fish can grow quite large.

However, they are somewhat less aggressive than Jack Dempsey Fish. The Electric Blue Jack Dempsey Fish was not bred in large quantities until recently.

Hey, do you have Jack Dempseys in a community aquarium? Let us know about your setup in the comments section below…


Dibyajyoti Bordoloi is the creator and author of FishCampRehab.com, a third-generation experienced fish keeper and owner of a successful pet breeding farm. He is also a member of the Center for Wildlife Rehabilitation And Conservation (Assam), the Marine Aquarium Societies of North East India, and the Kaziranga Nature Conservancy of Assam.

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