jack dempsey fish in aquarium

Jack Dempsey Fish Care: Types, Tank Setup, And Everything You Need To Know

The Jack Dempsey fish is an extremely popular species of cichlid due to their beautiful coloration, large size, and famous aggressive behavior. They’re big fish with a lot of personality which makes them popular among aquarium owners. However, because they can get big and be aggressive at times, it is important to know how to care for them properly.

This article will discuss how to care for your Jack Dempsey Fish including tank setup, diet, breeding, types, and more! Let’s dive in!

Jack Dempsey Care Items:

Jack Dempsey Overview

The Jack Dempsey’s scientific name is Rocio octofasciata. This species is part of the cichlid family and lives in the freshwater streams and rivers of Central America including Mexico, Belize, Guatemala, and Honduras. It can also be found in parts of the United States, Australia, and Asia. However, it is considered an invasive species in these areas and likely came into existence when aquarium owners dumped their pets into wild waters.

You’re probably wondering where the name Jack Dempsey came from. Jack Dempseys are named after an American heavyweight boxing champion in the 1920’s, William “Jack Dempsey” Harrison. Dempsey was considered a heavy hitter which aligns with this Cichilid’s archetypal body shape and semi-aggressive tendencies. However, with the proliferation of cichilds available on the market now, Jack Dempseys are more mellow than some of the more aggressive species such as Jewel Cichlids or Jaguar Cichlids.

Jack Dempsey Appearance

Jack Dempseys are beautiful fish. They have a typical oval-shaped cichlid body and are longer than they are tall. They have pronounced facial features as one might expect from a heavyweight boxing champion.

Part of their popularity comes from their variety of potential colors. They range from a dusky, rosy pink all the way to a dark, almost black color. There are multiple varieties (see below), but the most popular options are typically golds, blues, and pinks.

blue jack dempsey fish

Their color changes as they age with younger fish being typically less vibrant. Expect to find younger fish with a pale grey body with green flecks, while older fish become a deeper purple-gray with bright blue-green flecks. Additionally, their colors change depending on their conditions. If they’re stressed, they will get pale. If it is mating season, they will get darker and more contrasted.

Color Varieties

Electric Blue

Electric Blue usually refers to the Blue Acara, an African Cichlid. But the color variety doesn’t stop there! The Jack Dempsey also comes in Electric Blue. An Electric Blue Jack Dempsey is a bright neon blue, with black spots. This color is the result of planned breeding and does not occur naturally in the wild.

Black Blue

As the name suggests, this is another variation of blue Jack Dempsey. Their body is usually black or dark grey and they have a sprinkling of iridescent blue or purple spots. While this color variation can occur in the wild, it is rare.

Other Color Varieties:

With these species, there really are an abundance of vibrant hues. Some of the other popular color options include:

  • Green: This is the most common color. These fish have green spots with a dark grey, black, or brown base color.
  • Blue: The non-electric blue version. These fish have royal blue spots over a black body.
  • Gold: A gold Jack Dempsey has a golden orange body with blue or green spots,. Alternatively, you might see a dark brown body with gold spots.
  • Purple:  You’re probably catching onto the color patterns by now. This color variation has a dark grey or black body with purple spots.

How long do Jack Dempsey Fish live?

Jack Dempsey fish can live a long time! Aquarists report Jack Dempseys regularly living 8-12 years in ideal conditions so keep this in mind before purchasing one.

How big do Jack Dempseys get?

Jack Dempseys are big fish; they’re named after a bruiser of a fighter after all.

If they’re given a sufficiently large aquarium, males will grow to about 10 inches long and females will reach roughly 8 inches. If kept in too small of a tank, their growth will be stunted and they will not reach their full potential.

In addition to being long, Dempseys are also thick. Thick fish typically translates to more bioload in your tank (more waste). This is an important factor when considering filtration options.

Jack Dempsey Fish Temperament

Jack Dempsey fish aren’t the most aggressive cichlids, but they’re also not the least aggressive. This means they’re not a great option for community tanks. 

Like many other species of fish, they tend to become more territorial as they age. We all get grouchier with age, right? They’re also big fish so it is pretty easy for them to harass or eat smaller tank members. They like to stake their territory that typically includes a hiding place so they can retreat in times of stress. If any other fish wanders too close to “their” area, that is when the trouble starts.

Mated pairs can hang together in a large enough tank. Like most married couples, they will still squabble on occasion but as long as they have enough room, it should be ok. During breeding, other fish must be removed as the mated pair will target and kill anyone who could hurt their babies.

Another key warning – do not keep two adult (sexually mature) males together in the same tank. It is a recipe for constant fighting that will end with one dead fish.

We’ll dive more into potential tank mates below but your best bet for a community tank is a big tank with other cichlid species of a similar size and aggression level such as green terrors.

Jack Dempsey Habitat

When planning the ideal Jack Dempsey tank, it is recommended to try to recreate their natural habitat. This principle works well when designing tanks and making sure your fish are eating correctly. Recreate their natural environment for best results. 

In the wild,this species lives in slow-moving freshwater, ranging from murky rivers to lakes to swampy areas. They prefer warm water that is slightly acidic and has low light levels. They’re used to sandy, muddy substrates with natural features such as rocks and plants.

What is the best tank for a Jack Dempsey Fish?

These fish are big, which means they need a lot of space. For a single fish, we recommend a 55-gallon tank as the smallest tank size.

If you want to keep a pair for breeding, a 100-gallon tank becomes your new minimum. For either one of these tank sizes, you’re going to want to invest in an appropriate aquarium stand to support the weight, as it will easily be several hundred pounds.

With aquariums, bigger is better because it is easier to keep stable water conditions. However, these are large tank sizes so if this feels like too much, we recommend re-evaluating this species as your choice.

Ideal Water Conditions

Maintaining ideal water conditions is extremely important for maintaining a healthy environment. Use an aquarium testing kit to test your water and stay on top of any changes. This is our favorite test kit.

As mentioned before, this species inhabits warm waters that tend to be slightly acidic. The most important element of water parameters is consistency though. Jack Dempsey are often captive-bred which means they can adapt to a wide range of water conditions.

  • Temperature: 74°-85°F
  • pH: 6.0-7.0
  • GH: 3-8 dGH (50-133 ppm)
  • KH: 4-6 dGH (72-107 ppm)

You will probably notice the water temperature is pretty warm so adding an aquarium heater to your set-up is a good idea. Here is our favorite aquarium heater.

Ammonia and Nitrites should be zero and nitrates should be under 40 ppm. If you need help understanding more about water conditions, check out our tank cycling guide.

We recommend weekly water checks with your testing kit to make sure everything looks good.

Best Jack Dempsey Tank

When it comes to how to decorate your Jack Dempsey tank, you’ll want to try to duplicate their natural environment as much as possible.  Live plants can purify the water and offer hiding places, so include some in your tank if you can. This species will dig around so expect some uprooting. Another fantastic choice is driftwood, which may be utilized to make hiding places for your fish.

Best Substrate for Jack Dempsey Fish

We recommend sand or gravel for your Dempsey tank. Darker colors look awesome with this species and really help their colors pop. Dark brown or black are excellent choices.

We also recommend avoiding “cichlid sand.†Cichlid sand contains a crystallized form of calcium carbonate (CaCO3) which will leach calcium carbonate into your water, which increases will increase the water’s hardness and pH. Jack Dempseys tend to inhabit soft water, not hard water, so it will make their environment slowly less hospitable over time.

Lighting for Jack Dempsey Fish

No special lights are needed for this species. They’re used to murky waters in the wild so you will want to avoid continual bright lights. Too much light will stress them. You can also add in some floating plants (like hornwort) to shade areas of your tank. Standard LED aquarium lights will work just fine.

Filtration for Jack Dempsey Fish

Jack Dempsey are big fish, which means they have a big bioload, which means you need a significant filtration system to handle them. A high-power external or canister filter is the best type of filter for this species. Keep the flow low to moderate as Dempseys aren’t high current swimmers.

Jack Dempsey Fish Decorations

Now for the fun stuff Рdecorating the tank! Jack Dempsey fish enjoy a combination of open swimming spaces and larger pieces of d̩cor to establish their own territory. Think driftwood, rocks, and natural elements to create nooks and crannies so your fish can easily define their territory.

Plant Options

Plants are a wonderful way to give your aquarium a more natural appearance. We love them but if you’re looking to cultivate a beautiful planted tank, you’re going to struggle with keeping Jack Dempseys.

The Dempsey fish, like a number of cichlids, enjoy digging in the substrate. Jack Dempseys seem to exist at both ends of the spectrum. Some are known to destroy plants, while others seem pretty chill about their plant tank mates. It is luck of the draw with the type of fish you end up with.

They’re not super likely to eat your plants, like some other Cichlid species, but they will root them up and you’ll end up with floating plants in a planted tank. If you’re going to go the planted tank route, get heavier duty options like Java Fern or Amazon Swords.

Potential Diseases

We are not veterinarians at Aquarium Friend. The information below is intended for general awareness only. If you are concerned about the health of your fish, consult a fish health professional immediately.

This species is subject to infections and diseases that are common to all freshwater fish. One common issue they face is Ich. There are multiple treatment methods including raising the temperature 86° F (30° C) for a few days or adding medication to the tank. Ich is survivable if caught early enough.

Jack Dempseys are also prone to a disease known Head and Lateral Line Erosion (HLLE), also known as “hole-in-the-head” disease. As the name suggests, this disease manifests as holes on the head. Although the exact cause is unknown, poor diet, lack of water changes, or over filtration with chemical media such as activated carbon are all thought at potential contributors.

Additionally, Jack Dempseys are prone to skin flukes and other parasitic infestations, fungal infections, and bacterial infections. This is no different than any other species of freshwater fish. We recommend reading about common tank diseases so you can recognize and treat them early.

Feeding your Jack Dempsey

In the wild, most Jack Dempsey fish are predators that hunt live prey. They eat worms, crustaceans, insects, and fish. For keeping your fish healthy in your home aquarium, this implies that they need a varied diet that is high in animal protein.

Luckily, they aren’t fussy eaters, so pick a food that is convenient for you.

Processed dried foods, like pellets and flakes, are the cheapest option and easy to get. Look for pellets or flakes designed specifically for cichlids. We recommend adding in some additional frozen/live foods to add into the tank occasionally to help broaden the range of nutrients you’re providing.

Bloodworms and brine shrimps are popular options for this species. Insects like crickets and grasshoppers are also great choices.

Plant-based foods are likely to be rejected, so don’t waste your money on them. This is also the reason why a planted tank might work for this species; they’re not prone to plant nibbling.

How Often Should I Feed my Jack Dempsey?

Feed adult fish 1-2 times a day. Only provide as much food as they can consume within two to three minutes. You can feed juveniles more often, 2-3 times a day. This is a fish species you don’t want to overfeed. They already produce a lot of biowaste as it is, so adding extra food that decays in the tank will only spike the water conditions faster.

Jack Dempsey Tank Mates

Based on how often we’ve used the word aggressive in this fish care profile, you might be thinking Jack Dempseys need to be kept solo. That’s not necessarily true.

As a general rule, tank mates need to be a similar size with the same aggressive temperament. What this translates to on the day-to-day tank dynamics is that no one is eating your other tank inhabitants and they all have a chance if a squabble breaks out. Peaceful species will be harassed. Small fish like tetras and invertebrates like shrimps and snails are food.

Your best bets are fish like Oscars, Mbuna cichlids, convict cichlids, firemouth cichlids, Texas Cichlids, and silver dollars. Regardless of the species you pick, you need to be ready to rehome one inhabitant if the pairing doesn’t work.

Jack Dempsey Breeding

Jack Dempsey fish are not necessarily an easy species to breed in the home aquarium. It takes a lot of dedication and experience to get this right.

When a pair of Jack Dempseys are ready to mate, you will notice a color change, with their colors getting darker. The male will start pestering the female, especially if he is ready to mate before her. If a female rejects a male, then you will need to remove one of them as soon as possible, as he will continue this behavior until the female dies. Larger, bulkier males will be more successful at starting breeding.

As mentioned before, they will also attack other fish in your tank so we recommend putting your breeding pair in a separate tank.

You need the right conditions for spawning to be initiated. The water needs to be clean so plan to do regular water changes. Warmer temperatures help encourage spawning so you might think about warming with a heater.

After mating, the female will lay up to 500 eggs. She will deposit them on a flat surface such as decorations, the substrate, or the aquarium walls. Expect hatching to occur about three days later.

Like a lot of cichlid species, the parents will be attentive and take turns guarding the little ones. They will often dig holes in the substrate to protect the fry until they are free-swimming.

How to Sex Jack Dempsey

Male Jack Dempsey fish tend to be larger, with long dorsal and anal fins with pointed tips. Males also have larger heads. Female Jack Dempsey fish tend to have shorter fins that are less pronounced.

Do Jack Dempseys eat their babies?

Jack Dempseys typically do not eat their babies. However, if they are stressed or in less than ideal tank conditions, they might turn to eating their babies and need to be removed.

Jack Dempsey FAQs

How aggressive are Jack Dempsey cichlids?

While they are not considered to be the most aggressive cichlids, Jack Dempseys do have some level of aggression and territorial behavior. If your Jack Dempseys aren’t kept in a large enough tank with good conditions, then they can become aggressive and violent toward other fish. They do best when kept alone or with other similarly-sized, similarly-aggressive fish.

Can Jack Dempsey live with Green Terror?

Jack Dempsey cichlids and Green Terror cichlids can live together in a large enough tank. The species are similar in both temperament and size. If you keep these species together, expect some standoffs ever so often but these will rarely ramp-up to serious squabbles.

Do Jack Dempseys recognize their owners?

Like Oscars, it is believed that Jack Dempseys can recognize their owners. There are many reports of Jack Dempseys excitedly splashing around their tank where their preferred humans (typically the people who feed them) come close to the glass.


If you’re an aquarist that has been looking for a new species of fish for your new large tank, the Jack Dempsey cichlid might be right up your alley. They are beautiful and get big enough to make a statement in your aquarium. What’s your experience with keeping this species of fish? Do they have personality traits like other popular types of cichlids? Let us know how it goes!

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