Jack Dempsey: Care Guide, Breeding, Tank Size, & Disease

There are thousands of different fish you can opt for putting in your aquarium, but the truth is that not every fish is a good fit for every tank, nor for every tank owner. The Jack Dempsey fish is an interesting-looking fish species that you will find in North America and Central America in particular, but it is popular in aquarium tanks all over the world.

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Jack Dempsey, also known as Rocio Octofasciata, is named after the renowned Jack Dempsey because of its solid facial features. Like all fishes from the cichlids family, Jack Dempsy also shows signs of aggression. It acts territorial when kept in a tank with a few other fish. Therefore, they should be kept in a populated water tank.

When it comes to some species not being a good fit for everyone – the Jack Dempsey Cichlid is a great example, so here is a guide to help you see if an electric blue Jack Dempsey is the right fish for your tank.

Before you can figure out if this fish is a good fit for your aquarium, you need to gain a basic understanding of what this fish is; how it acts, what it does, and what it requires in order to thrive and stay healthy, as well as what kind of an aquarium is right for this bad boy of a fish.

Jack Dempsey Overview

The Jack Dempsey (fish), also known by its scientific name Rocio octofasciata, is a species belonging to the Cichlidae family. It is native to particularly Honduras and southern Mexico, but you will also find it in the United States, Australia, and Thailand, where it has been deliberately introduced and now forms part of the ecosystem. Having Jack Dempsey Cichlids in your aquarium can be great, but you need to know what you are in for, both to ensure that your Jack Dempsey thrives, but also that the Jack Dempsey tank mates are compatible. Here are some basic Jack Dempsey facts:

Information ChartJack Dempsey
Care Level: Intermediate
Temperament: Varies
Color: Dark purple-grey with colorful flecks; color changing
Lifespan: 8-10 years
Size: 10 -15 inches
Family Cichlidae
Diet: Carnivore
Minimum Tank Size: 55 gallons+(ideally 80 gallons)
Temperature: 72-86 ºF (22-30 ºC)
Water Conditions: 9-20 dGH water hardness / PH between 7.0 and 7.5
Tank Mate Compatibility Fish of similar size and with similar personalities

The Jack Dempsey naturally lives in still and swamp-like waters – often with plenty of weed and muddy or sandy river bottoms. The tank will have to be conditioned to mimic the tropical conditions the Jack Dempsey is used to living in, and you will also have to pay special attention to any future Jack Dempsey fish tank mates you might already have in the tank. The Jack Dempsey fish lifespan is approximately 8-10 years.

Jack Dempsey Appearance

These fishes have distinct colorations. They are long and have an oval shape. Their dorsal and anal fins are enormous compared to the body, and they have a big round tail.

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The actual color can vary from tones of grayish-brown to reddish-brown. The sides of the fish (head and fins) have a darker shade than the rest of the body. It has bright, tiny spots all over the body’s center and big darker ones on the caudal base.

The colors can change according to the moods and age of the fish. They can have different pink, golden, blue, and green shades. A sudden change in the color of the fish would signify its irritation about something.

Types of Jack Dempsey Fish

Jack Dempsey in tank water with another fish

The species is called Rocio octofasciata, and there is only one type of this feisty little swimmer, but there are multiple different colors you are likely to come in contact with if you choose to add a Jack Dempsey fish to the tank.

There is a pink Jack Dempsey, an electric pink Jack Dempsey, a platinum Jack Dempsey, and a yellow Jack Dempsey, and there is even the chance of an Albino Jack Dempsey!

There are all the same species, and only their physical appearance in terms of color can vary somewhat. The electric blue Jack Dempsey is known for being somewhat less aggressive, and also smaller in size.

The color of a Jack Dempsey fish can change and vary depending on its mood, almost like one of those mood rings that were temporarily popular in the late 90s, and stress and age are two of the things that can invoke these sudden changes in color.

Lifespan Of A Jack Dempsey

When successfully cared for and kept, this is a fish that will be around for a long time, with an impressive lifespan of 8-10 years – quite long considering its size.

They can grow quite well in a large aquarium. The average lifespan of these fishes is between 12-14 years. The Electric Blue Jack Dempsey can live up to 10-15 years. 

The babies are difficult to survive since they are very wild. Their parent fish can eat their babies due to their small size and hunger. However, these are unlikely possibilities in a tank. So, they can all grow into healthy sizes.

Jack Dempsey Size

A typical Jack Dempsey can grow up to 18-20 centimeters in length. Extensive care ensures their growth for about 25 centimeters in ten years.

The most common Electric Blue Jack Dempsey is about 8-12 inches as an adult. They grow very fast, almost 2-3 inches every year. The average size is 10-15 inches for a fully grown Jack Dempsy fish. Still, the females are usually slightly smaller than the males, and it will add a fantastic dash of glimmering color to your aquarium water. Proper food and pellets will help the fish to grow steadily in the tank.

Natural Habitat And Origin

This cichlid fish is a freshwater fish found in the freshwaters of Mexico and Honduras. It is also very widespread in Australia and Central America and is one of the only 30 aquarium fishes found in Australian waterways. 

These fishes are popularly found in a deserted quarry in Yamba called the “Green Pool.” There are no other natural populations of this fish in Australia. Due to the pool’s small size, the Jack Dempsey Cichlid fish has often been subjected to eradication. 

The appropriate temperature for this fish is 11 to 30 °C. However, they can also survive in cold temperatures between 8-10 °C. It is advisable not to keep them in high salinated water.

Jack Dempsey Care And Tank Setup

There is a very simple way of figuring out how to condition a tank for a Jack Dempsy fish, and it is something that works well no matter what kind of fish you plan to acquire. Always consider the natural living conditions of the fish, such as – in this case – the Dempsey fish coming from a tropical and warm climate with water full of weeds and natural hiding places.

Now let’s talk about Jack Dempsey’s care. You don’t have to be an expert to make a good Jack Dempsey fish owner, because while it can look a little hard and rough (just like the 1920s boxer it is named after) – it can also be quite a charmer! In terms of care, there isn’t much you need to do other than to make sure it does not bully other fish.

Jack Dempsey Tank Size And Specification

Try your best to recreate these conditions inside the aquarium and tank by providing appropriate plants, caves, other hiding places and keeping the water temperature just right. Jack Dempseys can appear shy as they always seem to be hiding, but they can be quite pleasant when they want to be, as long as they have that hidden away space to retreat to whenever needed.

These are adaptable fishes that can survive in a lot of water conditions. Beginners can also keep these gorgeous fishes as aquatic pets. 

The regular Jack Dempsey fish likes to dig a lot of soil inside a tank. Hence, it is better to keep these fishes with sand or gravel. Keeping them on the dark surface helps enhance their natural colors. The recommended tank size for this fish is a 100-gallon tank.

Optimum Tank Size For Jack Dempsey Fish

The optimum tank size for Jack Dempsey fish is about 100 gallons. They must be kept with different fish mates in a large tank due to their aggressive nature. A few fish in a large tank will trigger its territorial behavior.

Filter Type

Filtration is an important process to clear the waste from a tank. The bigger the size of the tank, the more waste there will be. Hence, an oversized filter will help cleanse the tank quicker and more effectively.

You can use a modern filtration device that mixes chemical, biological, and mechanical systems. They provide other significant benefits along with cleansing the water.


The substrate used in the tanks of a Jack Dempsey is gravel and sand. Since they like to dig a lot, mud or soil will create a messy affair. 

These fishes change their body color according to their surroundings and moods. Keeping them against a dark substrate will give them gorgeous dark hues.

Water Parameters For Jack Dempsey

Water Temperature

Jack Dempseys are originally freshwater fishes. Freshwater tanks with a 23-29 °C are the most suitable environment for this fish.

Water Flow Rate

The water must be flowing at a slow rate.

Ph Level

The water pH level for Jack Dempsey tanks should be between 6.0 to 7.0.

Water Hardness

Jack Dempsey is a soft water fish. The increased minerals in hard water are not suitable for hard water cichlids. The range of hardness should be between 3 to 8 dGH (50-133 ppm)

The water should not have any amount of ammonium nitrate. The level of nitrate in the water should be lower than 40 ppm.

Jack Dempsey Tank Landscape

Best Plants For Jack Dempseys

Plants secured safely inside a tank are the best plants for these species. As they are aggressive fishes, they can cause a lot of wear and tear inside the tank. Java Fern and Moss are a few of the most widely available plants for Jack Dempsey’s tanks.

Other plants that can provide penetrating roots and offer shelter are also suitable for cichlid fishes. Anubias and Vallisneria are two examples of such plants. Floating plants are also a great option as the fishes won’t bother them.

Worst Plants For Jack Dempsey

Plants loosely rooted in the substrate are the worst plants for Jack Dempseys. They have a habit of digging into the substrate. Loosely rooted plants can dishevel the water in the tank.

Decorations For Jack Dempsey

Dry leaves promote microbial growth and enhance the lighting inside the water tank. It is a great way to provide your fish with better surroundings inside a tank. 

Keep changing the leaves frequently, preferably twice every month. They decay pretty soon and can affect the quality of the water.

Lighting For Jack Dempsey

Jack Dempseys likes to stay alone and under covers. Too much bright light can affect the mood of the fish. The best lighting for cichlids would be the dim yellow light matching murky waters. The atmosphere inside the tank should be similar to the natural habitat of the fish.

Feeding Jack Dempsey

Best Diet for Jack Dempsey

Are you worried about what your full-grown Jack Dempsey will eat? Don’t be. They are carnivores, meaning they feed on meat, but most Jack Dempseys will eat pretty much any meat or meat-like thing provided it can fit in their mouths. To add some extra protein to their diet, you can always consider adding bloodworms a couple of times a week, as they are going to love it and benefit greatly from the nutrients found in these worms.

An adult Jack Dempsey tends to eat a couple of times a day, but don’t waste your time trying to convince them to eat plant-based food, as this will likely not be popular. The plus here is that you generally don’t have to worry about your new fish munching on your tank plants!

How Often Should You Feed Jack Dempsey?

Baby Jack Dempseys, at an initial age, can be fed around 2-3 meals a day for fast growth. However, adult fish are fed up to two times a day. 

Overfeeding can prove to be very harmful to the fish. Let them eat for 2 minutes after serving and then remove all the uneaten food. This will give them a smaller eating window and help you to avoid overfeeding.

Jack Dempsey Behavior And Temperament

Beginners are often surprised by the seemingly aggressive nature of the grayish-blue Jack Dempsey, and it is not unusual that you end up regretting your decision to make one a part of your tank. Their name is derived from the famous boxer and his demeanor. This is more a result of you as a tank owner being unprepared rather than the fish being unfit to live in harmony in an aquarium. The Jack Dempsey is also called a ‘beautiful beast’ because of its stunning colors and aggressive nature. 

Jack Dempseys can come across as aggressive when a better term would be ‘territorial.’ It dislikes sharing the tank space with other fishes, and it is not okay with the intrusion. It tends to stay in the back or middle of the tank, where it will defend its turf with everything it has got. They mostly form schools at a young age when they are quite excitable. 

This does not mean that it cannot live with other fish, and it generally does well with other Jack Demsey cichlid tank mates, surprisingly enough, or in a well-populated tank. 

The reason for this is that Jack Dempsey often takes on a bully-like role, and they may single out fish that keep to themselves, something that doesn’t happen as often if there are plenty of fish living in the aquarium. Providing the tank inhabitants with many different hide-outs and caves can also help reduce its territorial behavior. Each fish will have somewhere to go without imposing on any of the others.

If you have had fish with aggressive behaviors, you will be ready for what is to come, and you are therefore more likely to succeed in your Jack Dempsey ownership.

Are Jack Dempseys Alone Or Societal In Nature?

Due to their aggressive nature, they must not be kept in community tanks. They can be very territorial about their space and do not like to share it with other fishes.

However, if kept with many other fishes in a large tank, they can survive easily. It eliminates their idea of ‘personal space,’ hence, they will not feel territorial.

Jack Dempsey Tank Mates

Keep in mind that it usually isn’t a great idea to just let a Jack Dempsey fish into an already set up aquarium without first considering the likelihood of getting along with the fish already in there. Jack Dempseys has a habit of singling out lonely and exposed fish, so the smartest thing you can do is choose tank mates that are similarly sized and have a tough personality, just like Jack Dempsey.

Ideal Jack Dempsey Tank Mates

It usually gets along well with other jack Dempsey’s, as well as other cichlids, angelfish, cascarudo, rasboras, and more, so try to do a little research on the subject before you make your final decision. Species from the synodotis family are usually also a good mix, and loricariidae family species, silver dollar fish, and tinfoil barbs. 

For those wondering whether it gets along with, for example, an Oscar, the answer is a surprising yes! With both being aggressive fish species, it may seem like they wouldn’t get along, but they can make great tank mates if you condition your tank with multiple caves and more.

It is easy to think that an aggressive fish like the Jack Dempsey might benefit from a less crowded tank, but that would leave more fish alone and exposed, often making it a better call to fill your tank up a little (reasonably) so that the Jack Dempsey becomes part of a small crowd. 

As previously mentioned, it is recommended that you provide your fish with enough hiding places for everyone, as the Jack Dempsey is less likely to fight if nobody tries to enter its territory or claim its cave or space. If you remain unsure of which tankmates to choose, a knowledgeable employee at your local pet store may be able to help you choose.

Bad Tank Mates For Jack Dempsey

It’s better to keep your Jack Dempseys away from aggressive fish species. The fish is also incompatible with tetras, shrimps, and freshwater snails.

Breeding Jack Dempsey Cichlid

A clear sign that both the female and the male are ready for mating is that their color grows significantly darker, and then it is all about timing – both need to be ready at the same time, as an unwilling female fish could even get killed. The best way you can help the process is by making sure the tank is properly conditioned, with the correct water temperature, and the water should be kept clean and fresh. If you try to keep it closer to the upper-temperature recommendation rather than closer to the lower, then your jack Dempsey’s are more likely to get in the mood.

Cichlids will often have an easier time pursuing a female if they are on the larger side, and Jack Dempsey is no exception. If everything goes well, your colorful fish could end up having approximately 500 eggs that hatch after somewhere around 3 days, and they stick to all types of flat surfaces inside the aquarium.

An interesting thing about the Jack Dempsey mate is that the female fish and the male fish both share responsibilities for the babies once they are hatched, and they stay close to them to keep them safe from other species in the tank. Make sure you have provided the pair with a suitable place to have their babies, such as a nicely sized cave, and be responsible when you breed. 

Jack Dempsey Breeding Level


Jack Dempsey Sexual Dimorphism?

To distinguish between males and females of this species, you will have to notice their length. The males grow longer than the females. The males are around 15 inches (38 cm), and the females are about 10 inches (25 cm).

Jack Dempsey Common Diseases And Their Treatment

The most common diseases for Jack Dempsey are skin flukes, fungal, bacterial, and parasitic infections from protozoa and worms. Try catching them at an early stage to treat the diseases carefully.

The ectoparasite Ich, also known as White Spot Disease, is one of the health conditions the Jack Dempsey fish is known for sometimes battling. Still, other than that – it is considered a healthy species that is fairly easy to care for, especially if you have had aggressive fish species in the tank previously. 

Any plants, substrate, or decorations in the tank can contaminate the water and cause diseases. Hence, clean them properly before installing them inside the tank.

Facts About Jack Dempsey Fish

  • The Jack Dempsey fish is named after the famous 1920 boxer Jack Dempsey.
  • This species belongs to the class Actinopterygii and the family Cichlidae.
  • The Mexican Blue Frontosa and the Electric Blue Jack Dempsey are the most common nicknames for the fish.
  • They come in a variety of vibrant colors and patterns.
  • They have an exceptionally long lifespan of 15 years.

Is Jack Dempsey Fish Right For You?

Jack Dempsey fish are beautiful additions to tropical aquariums for their large sizes and extraordinary looks. The average cost of a commonly found Jack Dempsey is around $5 to $10. However, the electric blue Jack Dempsey is rare to find and costs a little more as well. This fish is larger than the regular size of other Jack Dempsey and have stunning iridescent blue scales.

In case you have a lot of peaceful and calm fish in your tank, Jack Dempsey is not the best option for you. They are quite aggressive in nature and cannot stay harmoniously with other peace-loving fishes in the tank. These fishes are territorial in nature and they do not have the reputation of being suitable fish for community tanks.


Can Two Jack Dempseys Live Together?

Yes, two Jack Dempseys can live together. Given you keep male and female fishes together, keeping them inside the same tank is safe. Nature will play its role, and they will be attracted to each other for breeding purposes. 

Do Jack Dempsey Fish Eat Other Fish?

Yes, Jack Dempseys can eat other fish. They are carnivorous animals that eat small fish, worms, and insects. However, you can give them frozen or live food inside a tank. 

How Can You Tell If Jack Dempsey Is Male Or Female?

The male Jack Dempseys are longer (15 cm) than the female ones (10 cm). Males also have bluish spots behind their eyes, whereas females have iridescent blotches all across their cheeks. 

How Long Can Jack Dempsey Live?

The average lifespan of Jack Dempsey is between 10-15 years.


Now that you know more about this remarkable fish species, it will be much easier to decide if it is right for you and properly condition a fish tank. It may not be a great fish for someone just starting out, but if this is something you are interested in, proper preparation and conditioning make anything possible. 

The Jack Dempsey fish has a great and colorful personality, which weighs up for its aggressiveness, and someone with a bit of experience or a will to learn. The Jack Dempsey fish price will depend on where you are located and your options. 

In the United States, the average price is usually somewhere between $10 and $15, and it will give you a colorful fish to keep in your aquarium for years to come if cared for correctly. Take a chance on this feisty fish and let it surprise you with its personality that can sometimes seem to be larger than life.

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