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Jack Dempsey Fish care guide: Detailed Info’ Pack

Jack Dempsey Fish

Jack Dempsey fish is a prototypical cichlid; a popular freshwater aquarium fish. It owes its name to the great, ruthless, ferocious and aggressive American boxing legend, William “Jack Dempsey” Harrison (professional career life 1919 – 1926). By the way, this G.O.A.T boxer still has his name in the list of top 100 boxers of all time.

Just like the boxer, the JD cichlids are predatory and exhibits ruthless aggression towards tank-mates. That’s besides the fact that they can be stocky and big in size. They are also boisterous big eaters.

You wonder why then are they still loved? Well, for the most part, they are very colorful besides having a great personality. Further, they are not overly pricey, are very hardy, easy to keep and breed.

Further, they can have a healthy life span of around 10 – 15 years.

The origin, habitation and differentiating the Jack Dempsey fish;

Mature Jack Dempsey cichlids are uniquely colorful, all in a year’s time; full body of golden spots with an iridescent light bluish/greenish with a contrasting background of dark purple. Besides, their dorsal and anal fin edges are conspicuously bright red. The spotting is particularly dominant in males than females.

Although the cichlids are now naturally found in places that are warm climatic conditions round the year, they are originally from Mexico, Guatemala and Honduras. 

The Jack Dempsey cichlid has morphed drastically within a century from Cichlasoma biocellatum to Rocio octofasciata.

Just like goldfish, they too naturally inhabit slow moving waters; sit near rocks and in caves. However, while goldfish thrive in colder waters, Jack Dempsey cichlids live in warmer waters of between 72 °F –86 °F. These warmer waters have low dissolved oxygen (DO) levels.

While they survive in a variety of environments, most tropical fish can’t. 

What are the ideal cichlid aquarium setup conditions and requirements?

Make no mistake, Jack Dempsey cichlids grow pretty big pretty fast. Let not the 2” and 3” length juvenile size deceive you. Most affects newbie aquarists. You’ll be setting your self-up for disappointment if imagine they won’t outgrow the size you are seeing them in at the dealer’s shop.

How big do Jack Dempsey fish get? This is a basic consideration to getting the correct Jack Dempsey tank size. Well, a mature and full grown Jack Dempsey fish attains a length of about 10” or more. What therefore does this Jack Dempsey cichlid size tell you? That for more than one JD, a 55 gallon is the minimum size you should be thinking of. A crowded tank will increase aggression of these very territorial and exploratory cichlids.

Subsequently, you are advised against keeping them in pairs but rather, in groups or singly. Pairing is only advised when breeding and which should be in a breeding tank.

The table below demonstrates the hardiness of the Jack Dempsey cichlids and their adaptability. Always, maintain these aquarium conditions;

Tank factorsTank TemperaturesAlkalinity/Carbonate hardnessWater pHAmmonia/Nitrite Level
Permissible ranges72°F –86 °F6 – 12 (Degrees)6.5 – 8.0NIL
ideal tank conditions

The fishes’ immunity is highly compromised when there is a spike of ammonia and nitrite in the tank. This comes as a result of waste breakdown. Ammonia especially is a serious irritant that corrodes the fishes’ lungs. This leads to severe internal bleeding and eventual death of the fish.

It’s also recommended that you test both the alkalinity and the pH of the tank waters at-least once a week. It’s to always ensure a stable pH in the aquarium. Water changes too of 20% – 30% of the tank water every 2 weeks are very necessary. They help on stabilizing the pH levels.

Further, just like fancy goldfish in very cold aquarium waters will require a heater (see article), so does your JD tank to maintain the ideal temperature. You’ll need a thermometer too to help watch the temperature changes.

Jack Dempsey cichlid aquarium lighting:

Illumination effect of lighting the aquarium results in a fantastic deep waters illusion. Subsequently, this results in the Jack Dempsey’s colors glowing brightly.

Presently, LED lighting is increasingly becoming the favorite lighting method, replacing the fluorescent lighting.  

Why is fluorescent lighting fading away? Well, here are some of the reasons;  

  • The light quality drops gradually by slow dimming in a short span of time; say 10 – 12 months.
  • While they are great in bringing out the tank’s gravel, plastic plants and ornaments, they are poor in highlighting the natural colors of the fish.  

To the contrary, LED lighting is gaining popularity as a tank’s preferred lighting choice because of;

  • Long life span coupled with less energy consumption,
  • Natural looking lighting with better tank coverage,
  • With customization, they can specifically highlight the fishes’ colors.

How to identify and choose the right cichlids for breeding;

As a general attribute across sexes, the Jack Dempsey fish has a laterally compressed body shape. This makes it look thin when facing it straight from the front. The body shape is an adaptation and camouflage hallmark for predatory carnivorous species of fish.

For breeding, you can either pair-up and separate from your flock that you’ve raised yourself or buy mature fish for that. The chosen pair should be placed in a breeding tank. This eliminates chances of fights and possible fatalities in the main tank as the courting takes place.

As a precaution not to inbreed, the recommendation is that you buy your different mature sexes from different dealers. If possible, this you should do at different times. Subsequently however, be ready for the somewhat task ahead of pairing them.

Now, if you are buying from the same dealer, be very keen to tell them apart lest you take home the same sex. Take time and observe their sizes and character while still in the dealer’s tank.

The good thing is, even juvenile Jack Dempsey cichlid(s) are still easily and clearly contrasting whether in size, physique or even mannerisms. You can easily pick them out. How you ask? The males (mature or juveniles) are dominating, big headed and generally are big bodied for their female age mates.

Further, unlike the female Jack Dempsey fish, their lower jaw hardly has the blue speckling. Additionally, their gill covers get more of pink color.

Why is the need to be this keen? Well, while it’s not too common, you could mistakenly take home paired males. Is it possible? Yes it is. Besides chances of them being siblings, they could just be tolerant to each other after one has dominated and subdued the other. 

The best juvenile size to buy for breeding is when they are upward of 3.5”. At this size, the dominant identification features are well elaborate to distinguish them.

Jack Dempsey fish breeding setup: How to pair adult cichlids for breeding:

One characteristic of the JD is that the males own their space. They can be overly aggressive in “protecting” their turf. Therefore, it’s the female that should be introduced in the breeding tank.

A caution however is, ensure the that the female Jack Dempsey cichlid is ripe with eggs. This will make her receptive the male’s “advances” for immediate spawning. Unfortunately, a mistake of introducing an unripe female can make her be mercilessly roughed up. Fortunately though, they end having good cohabitation, and if pairing is done right.

Where do they spawn?

Just as they naturally like to inhabit the bottom of the water body in the caves under the rocks, that’s where they’ll spawn too. However, even better would be if you can also avail a flat and clean stone under the rock caves on which they can spawn.

The male will fertilize the laid eggs which they’ll both watch over. On hatching in about 2-3 days later, they’ll put them in pits dug thereunder on the sand substrate/gravel. They’ll both vigilantly guard this nest. From there, they’ll herd the fry for about 8-10days till they are free-swimming.

You can feed baby Jack Dempsey fish on frozen baby brine shrimp to enable strong growth.    

Feeding: What is ideal Jack Dempsey food?

Firstly, a caution/reminder; the fish should only be feed what can be cleared in under two minutes. Anything beyond that indicates overfeeding. You want to avoid that to prevent water pollution when the excess feeds start decaying in the tank.

Now, educate yourself that JDs are carnivorous. Live, frozen of freeze dried foods are to a large extent, their main diet. Freeze-dried blood, black and earthworms, shrimps, ghost shrimps, minnows and crickets are some of their ideal and favorite feeds.

Additionally, carnivore pellets (both sinking and floating) as well as flake foods are all part of their diet. The good thing is that they are easily available feeds in the pet store near you.

How to identify and treating most common cichlid deceases?

Like all fresh water fish, JDs too are susceptible to ailments. The brighter side of this however is that, raising the tank’s temperatures eliminates most of these ailments. The common ailments are;

  • “Hole in the head” disease. This is also known as hexamita or head and lateral line erosion (HLLE). You identify it by spotting cavity and/or depression/pit like feature on the head and face. Besides the obvious weight and appetite loss, lesions may also develop along the lateral line.

While it’s very prevalent with poor tank water quality, nutritional deficiencies, hexamita parasite infestation and mineral imbalance also cause its occurrence.

Solutions: The multiple possible causes make it difficult to administer a “one fit all cure”. However, you can address each possible cause by;

  • Use approved anti-biotics to rid the tank of hexamita parasite,
  • Frequent water changes to restore water quality,
  • Improve on the diet to cure nutritional deficiencies.
  • Skin/gill Flukes: The fishes’ gills are infected by the notorious freshwater parasitic flatworm. As a result, a thick coat of slime and reddened gill membranes develops. Subsequently, the fish breathing ability is highly impaired. Besides siting the reddening gills, you’ll also note gasping for air. Further, you may as well observe body brushing and rubbing against any hard objects/surfaces in the aquarium.   

Solution: Raise the aquarium’s temperatures and add 1 tbspn/day of aquarium salt for a few days (or till you note improvement). The salt adds electrolytes and improves recovery from diseases.

  • Cotton wool disease: It’s a common fungi caused disease.Infected cichlids spots on the head, fins and scales, fuzzy whitish/grayish growth patches. The head tissues suffer visible erosion too. It results from poor water quality, feeding on dead fish remains as well as on decaying food remains. It’s an easily manageable though a contagious infection.


  • Salt bath immersions and other anti-fungal medications,
  • Upholding utmost tank hygiene,
  • Ensure fish safety and guarding against pet stresses and injuries. These increase exposure to this disease.
  • White spot-ich: Commonly referred to as Ich and caused by the protozoa parasite. You’ll easily identify it because the gills and fins spot small white dots besides fins cramping.  Additionally, the fish will exhibit lethargy, brushing against tank objects, diminished appetite as well as breathing difficulties.

Solutions: These include;

  • Raising aquarium temperatures,
  • Salt baths,
  • Introducing potassium permanganate to the tank alongside acriflavine.

Effects of cichlids to natural habitations;

Their Ease of adaptability, prolific multiplication rate and mostly their hardiness are some of their endearing attributes. However, the need to compete for space and food fuel their aggression and domination mannerisms.

These traits and attributes increase their survival chances no matter the environment. To the contrary however, these same traits and attributes are a risk to other pond/waterway’s lives. In-fact, their threat level in the wild to other has been equated to a nuisance pest.

Electric Blue Jack Dempsey fish;

With the right Jack Dempsey cichlid tank mates and in an appropriately sized tank, this cichlid is an amazing color morph show type fish. Its sparkling scales both on the cheeks and sides earned it the name “Morning dew”. That is the Spanish interpretation of its scientific name Rocio octofasciata.

While the standard Jack Dempsey fish is aggressive and can grow to 10” in size, the electric blue JD is in the contrary, less aggressive and smaller in size. Therefore, because of their low aggression, they are well tanked together with other Jack Dempsey types. The tank mates could include Jewel cichlid, Oscar and Silver dollar among others.

In the aquarium, you’ll find it hiding in the “caves” from under rock caves and driftwood decorations. Fine and deep sand/gravel is very good with its barrowing. It also nibbles on floating tank plants and overhangs which diffuse light and provide it with a good cover.

How do you distinguish Electric Blue Jack Dempsey sexes?

Well, it’s not too difficult. The dorsal and anal fins are well developed and elongated in males. In females however, they are short and rounded.  

What is the right aquarium size for Electric Blue Jack Dempsey Cichlid?

The ideal minimum indoor habitation for the Electric Blue Jack Dempsey fish tank size is nothing less of a 55 gallons tank. For all other ideal tank conditions, refer to the table earlier on in this article.

What are the best aquarium plants for Electric Blue JDs?

Besides JDs liking to sit and barrow at the bottom of the tank in rocks caves, they also love to hide under floating tank plants and overhangs.

Further, they will strongly nibble on these plants and naturally want to “re-set” the habitat.      

As a result, you should ensure that any live plants are thick-leafed. The plants should also be well and firmly rooted.

How do Electric Blue Cichlids breed?

Firstly, the EBJD is an egg layer, averaging 600 – 800 eggs on clean areas of; say rocks, wide plant leaves and even driftwood. All you need is to provide it with the right and enabling environment. How? You ask! Ensure to raise the tank’s temperatures to between 82° F – 85° F. Further, make the tank’s pH stable (well, a little acidic).

The fry is eventually free-swimming in 7-10 days after the eggs hatch in about 3 days of being laid.

To boost survival and health of the fry, you can start then off on baby brine shrimp diet. Alternatively or even complementary, flake foods (crushed) can be introduced too.


Jack Dempsey fish is a hardy and easy to care for pet fish. It also multiplies quickly and in very large numbers. As a result, they may overwhelm you. Therefore, you may consider giving them out to new hobbyists or return the excess to pet fish stores.

In-fact, because of the effects on natural habitations if not well managed its illegal in some countries to release them in the wild. You need a permit to do that. In absence of the options above, there are recommended ways of destroying them in without contravening the basic animal rights.