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Jack Dempsey Fish: Care, Feeding, and Breeding

Jack Dempsey fish are classic large cichlids in the aquarium trade for many good reasons. They are quite beautiful, with gold, green, and blue spangles.

What’s more, they are very hardy fish that can tolerate a wide range of water conditions. And it’s not at all difficult to breed these fish, allowing you to witness the intensive care that cichlids provide their eggs and young.

Overall, the Jack Dempsey fish might be the best large cichlid to start out with for these reasons.

Jack Dempsey Fish

Getting to Know Jack Dempsey Fish

The native habitat of Jack Dempsey fish is in Southern Mexico and Central America as far south as Honduras.

They are closely related to many Central American cichlids, including Convict Cichlids, and they have similar care needs.

For one, the Jack Dempsey enjoys the same hard water and moderate temperatures. And they really enjoy rocky aquariums where they can move gravel around and dig holes.

Jack Dempseys are a good choice for aquarium keepers who want something with a little more personality and size.

They are large fish but don’t grow to be unmanageably so. And they are aggressive fish – but not so aggressive that you can’t keep them with well-chosen tank mates.

So what else is there to know about the Jack Dempsey fish?

  • Common Name: Jack Dempsey fish, Jack Dempsey Cichlid, Mexican Blue Frontosa
  • Scientific Name: Rocio octofasciata
  • Origin: Southern Mexico to Honduras
  • Length: 8 to 10 inches
  • Aquarium Size: 55 gallons
  • Temperament: Semi-aggressive
  • Ease of Care: Very Easy

Why are they called Jack Dempseys?

Why are they called Jack Dempseys?

The Jack Dempsey fish has an interesting name: it was taken from the legendary boxer Jack Dempsey, who was known to be very aggressive in the ring. In fact, Jack Dempsey was the world heavyweight boxing champion from 1919 to 1926. He also had very strong facial features and if you look at the fish’s head you might see some resemblance. So someone decided that the fish species reminded them of the famous boxer and here we are.

All that aside, the Jack Dempsey does not quite live up to its name. Back in the early 20th century when this fish species entered the aquarium world, they were some of the feistiest fish around. However, this was an impoverished world compared to what we have in pet stores now, with few freshwater species more exotic than guppies and barbs.

Nowadays, the “legendary” Jack Dempsey fish is on the tame side compared to its Neotropical relatives. For example, the Umbee Cichlid and the aptly named Red Terror are so vicious that they require species-only tanks. Jack Dempseys can at least live with fish species too large to be eaten or easily bullied.

Electric Blue Jack Dempsey

Naturally hued Jack Dempsey cichlids are already colorful fish. But the Electric Blue Jack Dempsey takes this to a whole new level. They are completely covered in iridescent blue scales with black mottling. They also have a stunning orange to crimson red eye.

Electric Blue Jack Dempseys are also a more peaceful fish than their wild colored cousins. They tend to be less territorial fish and get along well in medium to large fish community tanks.

But as beautiful as they are, it is not all good news when keeping an Electric Blue Dempsey. They have been highly inbred to get those crisp blue colors. And as a result, they tend to be more sensitive to poor water conditions, especially ammonia, nitrite, and nitrate levels.

The Electric Blue Jack Dempsey price is also much higher than that of a standard Jack Dempsey. If you see both in a pet store the Electric Blue can cost 10 times as much. So think carefully before choosing these wonderful, slightly more sensitive fish.

Caring for Jack Dempseys

Jack Dempsey fish are hardy and easy to care for so long as you provide enough space for them and any other aquatic life you keep alongside these cichlids.

Jack Dempsey Fish Lifespan

Large fish tend to be more long-lived than small fish and the Jack Dempsey is no exception. 10 years is an average lifespan for these fish, with a few years under or over not uncommon.

Minimum Tank Size for Jack Dempsey fish
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Minimum Tank Size for Jack Dempsey fish

The only real complication to Jack Dempsey cichlid care is ensuring that you have enough space for fully grown adults. They aren’t monster fish in terms of size, like an Arowana or Peacock Bass. But at 8 to 10 inches long as an adult you still need to plan a little.

55 gallons is an absolute minimum tank size for a full-grown Jack Dempsey fish. But this is best for a small fish; 55 gallon tanks are 12 inches wide at the longest dimension, which is a tight turnaround for a mature fish.

A 75-gallon tank is far more comfortable if your Jack Dempsey fish is on the larger side. More space also allows you to keep more tank mates with them. And should you have a more territorial fish it won’t bully them so easily.

Jack Dempsey Cichlid Aquascaping

Another aspect to consider when keeping Jack Dempseys is their love for aquascaping. Like many large cichlids, they love to dig in the substrate. And worse, they will often tear at and uproot any plants they can. Not always but often enough that you should plan for it.

If you have one or more in a mood to breed all of this aquascaping activity intensifies. So what can we do about this?

Your substrate choice will affect how your tank looks. Fine sand can actually be a good choice because it does not pile up so easily. Any holes the Jack Dempsey fish try to dig will remain shallow and backfill into themselves before getting too deep. You can also try pebble substrates; only the most determined fish will be able to remove all of the rocks from a spot. But most gravel bottoms will be turned into little hills and pits.

You should stick to either silk or plastic plants, floating plants, or especially hardy plants. Good floating plants include red root floater, hornwort, and duckweed.

There are also several tough live plants that can survive the onslaught of a determined Jack Dempsey fish. Anubias and Java Fern are commonly chosen for a cichlid community tank because they are epiphytic plants. This means that they don’t grow in the gravel; both plants attach to hard surfaces like rocks and driftwood.

Jack Dempsey Fish Water Quality
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Jack Dempsey Fish Water Quality

Like many Central American freshwater fish, Jack Dempseys prefer moderately hard (mineralized), alkaline water conditions. This makes them great fish for beginners because their water needs no treatment. Right out of the faucet, tap water in most of the world tends to be slightly mineralized and moderate to high in pH (7.0+).

Jack Dempsey fish are also not very sensitive to elevated levels of ammonia, nitrite, or nitrate. You still should keep up with water changes because these compounds are not at all healthy for them. But overall they are less likely to die than other freshwater fish.

Temperature-wise, Jack Dempsey fish prefer a range between 73-78°F. They should be kept neither too warm nor too cold. Jack Dempseys also don’t tolerate much salt so don’t add too much aquarium salt except as a tonic or to treat conditions like anchor worms.

What do Jack Dempsey Fish Eat?

What do Jack Dempsey Fish Eat?
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Jack Dempsey fish are entirely carnivorous. They will eat other fish if they are small enough but they are mostly opportunistic predators. Worms, insects, insect larvae, small snails, shrimp, crayfish, tadpoles, and anything else small enough to eat is fair game.

So start with animal protein and variety when planning out a meal plan for your fish. When young you can start your Jack Dempsey fish out on brine shrimp, bloodworms, tubifex, and other items.

As they grow older, you might be tempted to start offering feeder fish. But I don’t recommend feeding a Jack Dempsey cichlid other fish because the quality is usually tremendously poor. Feeder fish are full of diseases like ich that they can pass onto the fish that eats them. They are also low quality and not fed well. Overall you will be doing your fish a favor by sticking to prepared and frozen foods.

But carefully chosen live foods like earthworms and ghost shrimp are a risk-free treat for an adult Jack Dempsey fish.

A high-quality pelleted food can also be the basis of their diet. A formula that is rich in protein is the best food for Jack Dempsey fish, such as Omega one cichlid pellets. Avoid formulas that use a lot of wheat, starch, and other vegetable fillers that offer no nutrition to a carnivorous fish.

Good Tank Mates for Adult Jack Dempsey Fish

Choosing tank mates for a Jack Dempsey cichlid should be done carefully. If you have a large tank (75+ gallons) then it will be much easier to keep multiple aggressive fish in the same tank.

But if the tank is smaller then I recommend ensuring that the Jack Dempsey is the dominant fish. Also, you should choose only dither fish that are too large to be eaten and fast enough to not be attacked. Good dither fish options include Giant Danios, Silver Dollar fish, Tinfoil Barbs, and Rainbowfish.

And if you have a big tank and want to try a cichlid community? The many species of South American cichlids are a good place to look. Green Terrors (Andinoacara rivulatus) are another fish with a mean name but semi-aggressive nature. Oscar fish are also well matched to Jack Dempseys.

Occasionally they may square off, with lip-locking and threat displays. But so long as you have enough tank space and you’ve chosen similar, semi-aggressive cichlids as tank mates then any fighting should be brief.

You may see lip-locking wrestling matches between cichlids. These are competitive bouts that arise when flared fins and aggressive dancing do not impress a rival. Usually, a winner will be decided and the loser chased off. But even a mated pair will lip-lock sometimes to settle domestic disputes.

Truly aggressive cichlids should only be chosen if you have a very large tank (125+ gallons). Midas cichlids, Red Terrors, Umbees, Red Devils, and many other Neotropical cichlids are both larger and meaner than most Jack Dempsey fish. So long as they have space to form their own turf you might be able to get away with it.

Another way to create mixed cichlid community tanks is to raise a group of smaller fish together. This way, they grow up used to one another and any one fish isn’t as likely to try claiming the entire tank for themselves. While it takes a lot of patience it is also the safest way to keep many different kinds of cichlids together without fights or deaths.

Breeding Jack Dempsey Fish

Being one of the most popular freshwater fish in the hobby it is natural to want to try and get a breeding pair for yourself. Jack Dempsey fish are not too difficult to breed so long as you get a pair that accept one another…

Breeding Jack Dempsey Fish
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Sexing Jack Demsey Fish

Jack Dempseys are sexually dimorphic; meaning you can tell the sexes apart by looking at mature fish. But it is not very easy; the differences are subtle and almost impossible to see in immature fish.

In a male Jack Dempsey fish, the dorsal fin and anal fins have distinctive points. Most cichlid males have pointed fins. Female Jack Dempsey fish don’t usually have these points – but sometimes you may find a female with them.

The blue and gold spangling of male fish are also more intensive – except on their cheeks (gill cover) below the eyes. Female fish usually have spangles that extend below the eye and onto the cheek. When fully grown a female will also be noticeably smaller and plumper than a male.

If you have Electric Blue Jack Dempsey fish, the only way to tell is the stoutness of the body and rounded fins in a female. Otherwise, they are just as vibrantly blue as any male.

You can also use behavioral cues to tell the sexes apart. Mature male fish will chase after females to get their attention and be proactive at forming territories and displaying at rivals.

Introducing a Male and Female Fish

If you haven’t raised a male and female fish together, introducing them into the same tank can sometimes be a dangerous affair. Remember, the Jack Dempsey cichlid is still territorial. And if a female is not ready to breed the male can become very aggressive, even harassing her to death.

Adding a tank divider is the tried and true method of allowing two fish to get to know each other. They will be able to see one another and sense each other’s hormones since they are sharing water. This way the female will also have time to ripen with eggs and become more receptive to the male.

Once you remove the divider after a week of sharing space, watch both fish carefully. They may not take to each other and vicious fighting can erupt. A bit of lip-locking is normal between even a mated pair of Jack Dempsey fish. But fast, aggressive chasing around the tank and fin-nipping is not.

Spawning Jack Dempsey Fish

Once your breeding pair seems stable they will likely spawn in no time at all. It is best to keep your pair in a breeding tank of their own because like all cichlids, Jack Dempseys become truly vicious towards other fish before, during, and after spawning.

The eggs are laid on a hard surface, such as a flat rock or overturned flower pot. The female will spend her time fanning the eggs with her fins to oxygenate them while the male patrols the borders of the tank.

Within a week the eggs will hatch At which point you will see young fry clinging to the rocks for the first 48 hours while they absorb their yolk sack. The fry then become free swimming and willing to eat baby brine shrimp nauplii and other tiny foods. You can also buy a commercial fry food, formulated and sized to meet their needs.

Over the weeks your juvenile Jack Dempseys will grow a couple of centimeters long and start to swim off on their own. At this point, you should look into rehoming them to friends and local pet stores.

In Conclusion

Jack Dempsey fish for sale are hardy cichlids that don’t grow too large and will eat just about anything you offer them. They also come in a gorgeous electric blue color morph and are even easy to breed if you are interested. I think they are one of the best cichlids to try if you are keeping large fish for the first time and don’t want too much of a handful.

More Frequently Asked Questions about Jack Dempsey Fish

Is Jack Dempsey fish Aggressive?

Jack Dempsey fish are semi-aggressive aquarium fish. They are much meaner than mollies and other peaceful fish. But there are also fish that simply can’t live with any tank mates at all. So long as you provide plenty of tank space and choose carefully, you can keep Jack Dempseys with other fish.

Can Two Jack Dempseys Live Together?

You absolutely can keep two Jack Dempseys together. It will be difficult to introduce them though, especially if they are the same sex. The best way is to raise two fish together when young. Or use a tank divider for two adults so they get used to one another over time before sharing the same space.

Can Jack Dempsey fish be Alone?

Jack Dempsey fish do fine when kept alone. A few fast dither fish as tank mates is also a good idea. But if you don’t have enough space, a lone Dempsey will simply look forward to your daily visits.

What Tank Size do Jack Dempseys Need?

55 gallons of space is an absolute minimum for an adult Jack Dempsey fish. And 75 gallons is even better since the extra width (18 inches vs 12 inches in a 55-gallon) is more comfortable for them.

Jason Roberts
About Jason Roberts
Jason is an aquarium fanatic that has been a fish hobbyist for almost three decades.