Jack Dempsey Fish 101: Size, Tank Mates, Diet & More!

For anyone who’s spent some time in the aquarium hobby, you’ve probably come across one of the most popular Cichlids out there: the Jack Dempsey. Named after one of the greatest boxers of all time, the Jack Dempsey fish have both striking looks and personality. They’re fierce, fun, and a sight for sore eyes-the perfect fish for anyone looking for the exceptional.

The table below gives a quick overview of the Jack Dempsey fish profile:

Profile AttributeValue
Care DifficultyIntermediate
Lifespan8-15 years
DietCarnivorous
Color(s)Various (dark gray, purple, blue, gold, pink)
TemperamentAggressive (can sometimes be shy)
Maximum SizeUp to 10-15 inches
Minimum Tank Size80 gallons
Tank SetupFreshwater, tropical, with hiding areas
Family Cichlidae
CompatibilityBest kept with similarly-sized and temperament fishes

Below is our Jack Dempsey fish care guide, continue reading to know more about its appearance, breeding, lifespan and more.

Overview

The Jack Dempsey fish (Rocio octofasciata), is a species of Cichlid also known as the Mexican Blue Frontosa. Belonging to the Cichlidae family, the Jack Dempsey is one of the most popular fish in the family. Now, you might be wondering what’s up with its name; the Jack Dempsey gets its name from the famous 1920s boxer, perhaps due to its similarity in looks and nature. These fellas are a beautiful species, no doubt about it, but they’re no sweet darlings; Jack Dempseys are as fierce as they come.

In the wild, Jack Dempseys hail from the tropical waters of Central America. From Mexico to Honduras, this unique fish was slowly introduced to other parts of the world such as Europe and Southeast Asia. Jack Dempseys typically live around slow-moving swamps, canals, rivers, and even ditches. They’re a hardy bunch capable of surviving even in the harshest of waters. 

To match their hostile natures, Jack Dempseys are also hardcore carnivores. They love their meat, whether live or frozen, and might even take a munch out of their little neighbors (eek!). But if you have a community tank, don’t write them off your list just yet. While aggressive, that’s not all they are. With the proper measures, Jack Dempseys can be an exciting member of a community, giving you endless fun and entertainment.

Appearance

Partly because of their strong, and prominent features, this Cichlid was named after the  great 1920s heavyweight boxer Jack Dempsey. At first, they often appear as light-colored juveniles. The’re oval bodies can appear in shades of gray or tan, with subtle turquoise splattered around their bodies. As Jack Dempseys mature, they become a daunting dark gray-violet, speckled with bright blues, greens and golds. 

Jack dempseys are a bit like chameleons; they change color in response to certain stimuli or environmental changes. These color switches occur when they’re stressed out, as well as when they’re breeding. In fact, Jack dempseys darken when breeding, looking almost black.

Upon adulthood, male Jacks develop long and pointy dorsal and anal fins; a feature absent in females of the species. Instead of that, female Jacks get more spotted and colorful gill plates than their male counterparts. 

At present, you can find Jack Dempseys with a multitude of colors from pet stores. These colors can range from Purple to Gold, Electric blue, and pink. The Electric blue Jack Dempsey is a natural genetic variant of this Cichlid. It’s also quite possibly more popular than the wild-type Jack dempsey. It boasts a bright royal to light blue color combination. Compared to the wild-type variety, the Electric Blue Jack is also less aggressive and more fragile in nature. 

Average Size

Believe me when I tell you-these fishes can get pretty huge. The average length for any adult Jack Dempsey bounces between 10-15 inches! It’s usually the males that reach 15 inches, though this also depends on the care you provide your fishes. 

Lifespan

Good news! Jack Dempseys are notoriously long-lived. They have a generous life expectancy of around 8-15 years. While that seems like a long time already, this is only the average. In fact, with  proper care and love, these large Cichlids can exceed even 15 years!

Jack Dempsey Fish Care Advice

Yes, Jack Dempseys are named after a famed boxer for a reason; they’re hostile, territorial, and perhaps they will take a bite out of small fishes. But that’s not all that they are; Jack Dempseys are also fun, amusing, and sometimes even shy! 

With the proper tank setup, mates, and water conditions, these fishes’ less-than-friendly attributes are easily curbed. So, if you’re interested in these large, popular, (feisty) beauties, then keep on reading.

Tank Setup

These spunky fishes usually spend their time in the middle to the bottom of the water column, so choosing a substrate is very important. Jack Dempsey fishes prefer a soft, dark, sandy substrate over anything else. Since these large fishes are always digging up the substrate, a soft texture works well for them. This also prevents any injuries your little boxer might get for digging. In fact, many owners note that their Jacks become much more vibrant and healthy-looking when placed in a tank with this type of substrate.

When it comes to ornaments, it’s probably not a good idea to place a lot of vegetation in your tank. Jack Dempseys are infamous for uprooting aquatic plants. Some argue however, that Jacks don’t always destroy plants, it all depends on if they like it or not; floating plants, for example, are great choices. Alternatively, Jack Dempseys seem to hate fake, plastic plants. Instead of that, you should invest in hiding places. Make sure your tank has lots and lots of nooks and crannies, caves and whatnot. The main reason for this is that while aggressive, Jacks can also be a tad shy. They need their caves not only as a hiding spot, but also so they have their very own territory in the aquarium. 

Once you’ve got that down, install a water heater. Remember that Jack Dempseys are tropical fish, so you need a heater to keep the temperature in an ideal range. After that, you can just add any basic filter, and keep your tank dimly lit. These guys aren’t too fond of bright lights, since they’re used to murky swamps and even ditches.

Water Parameters

In their native habitats, Jack Dempsey Cichlids are commonly found in murky waters. These can be rivers, swamps, and even unideal ditches. Indeed, Jacks are extremely hardy tropical fish, able to survive in the most desperate conditions. But of course, we don’t recommend you test your Jack Dempsey’s limits. Once they are rescued or placed in a much better environment, it shows a night and day difference in the Jacks’ colors. 

Water Parameters:

  • Temperature: 72-86F or 22-30C (keep it mid 70s to low 80s)
  • pH levels: 6.0-7.0
  • Hardness: 9-20 dGH
  • Water flow: 

Apart from maintaining the mentioned parameters, 10% weekly water changes messy eaters.

Common Diseases

These stunning creatures are generally hardy fishes. If you can remember, Jack Dempseys are so hardy that they can manage to survive in canals and ditches. However, they can still be prone to the common ailments of all tropical, freshwater fish, such as:

  • Hole-in-the-head disease
  • Worms, flukes
  • Ich
  • Fungal infections
  • Bacterial infections

Among all those mentioned, Ich and Hole-in-the-head are the most common in Jack Dempseys. Hole-in-the-head, or Hexamita, is typically common among Cichlids. Caused by a parasite, the primary symptom of Hexamita are lesions in the body or head of the fish; hence the name ‘hole-in-the-head’. Hexamita is caused by a parasite which causes lesions. These lesions then allow bacteria to enter your fish, becoming very much fatal to your pet. While not entirely certain, Hexamita is widely believed to be caused by poor water conditions, diet, and a deficiency in certain vitamins and minerals. 

Meanwhile, you’ve probably already heard of Ich, also known as White spot disease. Ich is caused by the protozoan Ichthyophthirius multifiliis, and manifests as fuzzy white tufts in fish bodies. Your pet becomes itchy when ailed by Ich, and will therefore try to rub itself on various ornaments. Thankfully, Ich is easily treated by raising the water temperature in your tank, as well as some accessible medication.

Like almost all common fish diseases and illnesses, Ich and Hexamita are both highly preventable. To avoid dealing with these ailments, perform at least 10% water changes weekly, install a proper filter and heater, and thoroughly clean any new ornaments before putting them in your tank. Other than those, make sure to feed your Jack Dempsey fish a well-balanced, and nutritious diet regularly. 

Tank Size

Much like their namesake, Jack Dempsey fish are no featherweights. These fishes can get quite large (15 inches!), so naturally, they would need an equally huge aquarium. To be sure, you’d need at least a 50-gallon tank. We recommend however, that you settle for an 80-gallon tank, just so your fish can be more comfortable, and you’d have more space for tank ornaments. Jack Dempsey fish can also get more aggressive when they feel trapped or cramped. An 80-gallon tank should dispel that problem nicely.  

Diet & Food

They’re big, they’re tough, and they sure love their food! Well technically, Jack Dempseys are omnivorous; they just really love the occasional meaty treats. This is the reason why these Cichlids are often thought of as carnivores. Back where they’re originally from, Jack Dempsey Cichlids devour anything from worms, crustaceans, to insects and other fish. They’re big, messy eaters and are generally hassle-free to feed (cleaning up after them is a different story, however). Jacks enjoy eating in general, so you won’t have much trouble thinking about what to give them. 

Jack Dempsey Fish suitable food includes:

  • Crickets/grasshoppers/fruit flies
  • Bloodworms
  • Shrimp or Cichlid pellets
  • Fish flakes
  • Freeze-dried krill
  • Frozen Brine shrimp
  • Daphnia 
  • Blackworms

When it comes to their schedule, feeding them for around two minutes, twice a day would be ideal. When feeding, remember to cut up large pieces of food so they can easily fit into their mouths. Apart from that, remember not to go overboard with the poultry or beef meat If you wish to feed these. These are treats given very sparingly (if you must) and not as a daily staple. 

Tip: Previously, we’ve mentioned how the Jack Dempsey fish often uproots, or destroys aquatic plants. To avoid this destructive habit, you can feed your fish blanched cucumber and lettuce, to get it out of their system. Voila! Your tank plants are safe (for now)!

Jack Dempsey Fish Breeding Behavior

For those of you who have fallen in love with these beautiful aquatic beasts, good news: they’re easily bred in captivity. Jack Dempseys don’t have strict spawning requirements, so the process is largely doable. The only thing you need to really worry about is their increased aggression during breeding season. 

First things first, try and set the temperature of your breeding tank to around 84° F-85° F, or around 28° C. If your Jack Dempsey fishes are in the mood for some lovin’, their colors darken to almost black. These fish produce a ton of eggs, sometimes up to 500 eggs at a time. The females deposit these eggs all over the tank, under rocks, ornaments, in the substrate, anywhere they please. These scattered eggs take about 3 days to hatch, during which the parents guard them religiously. 

What’s surprising about these aggressive, scary-looking fish, is that they’re actually wonderful parents. Both Jack Dempsey parents are attentive, and caring helicopter parents. As a matter of fact, they even pre-chew food before feeding it to their fry (much like birds). Jack Dempsey fish parents sometimes even dig holes to keep their eggs safe from lurking predators. However, when these new parents become stressed, they can also end up eating their beloved babies. They get stressed out when something in their environment is amiss. This unfortunate event is thankfully easily avoided, as long as you keep their environmental conditions optimal and stable.

Jack Dempsey Fish Tank Mates

Okay, so the Jack Dempsey isn’t going to be the most versatile, easy-going fish in your aquarium. In fact, when looking for ideal tank mates, you should direct your eyes on medium-sized, semi-aggressive fishes, or fishes that can defend themselves. Too peaceful fish can end up being bullied, and ultimately killed; the same goes for small fishes that fit in Jacks’ mouths. Tetras, crustaceans, or invertebrates are a bad idea, because these are common meals for the Jack Dempsey back in their native homelands

Suitable Tank Mates for Jack Dempsey Fish:

  • Red Devil Cichlid
  • Convict Cichlids
  • Deboise
  • Oscars
  • Angelfish
  • Silver Dollar fish
  • Clown Loaches
Tip: Ironically, Jack Dempseys are actually more amicable when kept in community tanks with a good amount of other fishes. In fact, they become more hostile when kept with only a couple of other fish species.

Jack Dempsey Fish Temperament

Like most Cichlids, Jack Dempseys have an aggressive and territorial tendency. However, the Jack Dempsey fish is not an entirely hostile fish. In fact these aquatic boxers can get along with many fish species in a community tank. The more members in a community, the better the Jack will behave. They’re not always just aggressive either. Jack Dempseys are actually more multifaceted than you would think. While it’s true that they can be hostile, they can also be immensely shy and amusing. They’re not bruisers, though they have these tendencies.

Jacks are boisterous fishes by nature. They’re fun, smart, and endlessly entertaining. Many owners even report their Jack Dempsey having  quirky behaviors in the tank. These are intelligent fishes that sometimes hide around in pots or other ornaments in the tank. 

Conclusion

As a final word, the Jack Dempsey is not for the faint-hearted. Because of their less-than-peaceful, and territorial nature, these fishes are not for beginner aquarists. In fact, they’re better suited to those with a tad more experience in handling aggressive fishes. If you’ve got a mind to get one of these fishes however, you won’t be disappointed. Jack Dempseys not only have an arresting beauty, but they’re also hardy, tough, and immensely amusing aquatic pets. Needless to say, having one of these in your tank will surely catch everyone’s undivided attention. 

Note: Please consider the environment before printing this Jack Dempsey Fish care sheet.

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