Aquarium Fish

Jack Dempsey Fish

The Jack Dempsey fish is a fairly popular Central American Cichlid and is named after the famous boxer from the 1920's. The common name for the Jack Dempsey may make you think that this fish is a bruiser. But, given the right setup, it can be a good tank mate if kept with similar cichlids. They will get more aggressive the more cramped they feel, especially if you have a mated pair. They will hold their own against more aggressive tank mates. Provide them with a cave or other territory they can call their own and they should settle in quickly.

The Jack Dempsey fish can be very hardy once acclimated to your tank and should live for a very long time if properly fed with a varied diet. Also, please keep in mind that they have no problem eating smaller tank mates.

If you have a mated pair you will soon find out that they breed easily and are remarkable parents. They will need a sandy or smaller sized gravel bottom so that they can dig a pit to transfer the fry to once they hatch. The adults will then guard their fry against any and all comers! You may need to remove the other fish from the tank if they become too dangerous to the other fish in the tank. Or use an aquarium divider to prevent any aggression.

The Jack Dempsey Fish can be a very cool fish to keep if you have the space and compatible tank mates. It's a very nice looking fish and they have great personalities.

Jack Dempsey Fish Pictures

Jack Dempsey Cichlid
Jack Dempsey
Electric Blue Jack Dempsey

Jack Dempsey Fish Video

Jack Dempsey Care

Scientific Name : Cichlasoma octofasciatum

Common Names : Jack Dempsey Fish, Electric Blue Jack Dempsey

Care Level : Easy

Size : Anywhere from 6 - 10 inches (15 - 25 cm)

pH : 6 - 8.0

Temperature : 75°F - 80°F (24°C - 27°C)

Water Hardness : 5° to 15° dH

Lifespan : 10 - 15 years or longer

Origin / Habitat : Wild caught specimens originate from Central America, Guatemala, and Southern Mexico but hobbyists usually will be buying a farm raised fish. They are often found in slow moving rivers and canals in Central America.

Jack Dempsey Fish Temperament / Behavior : If given a large enough tank (55 gallon or larger) you may not see them being overly aggressive. If you cramp them into smaller tanks, like most fish, they may become more aggressive. Watch them closely.

Breeding Jack Dempsey / Mating / Reproduction : If you have a mated pair, it is very easy to breed them. Give them a pot or cave structure and the female will drop the eggs with the male following after her fertilizing the eggs. Once the eggs hatch the parents will move them to a pit and defend them from tank mates. The parents can get very aggressive during this time and do a remarkable job of protecting their young fry. They will breed often and can produce hundreds of eggs per spawn. It is important to prepare for this and breed them responsibly.

Aquarium Size : 55 gallon minimum for one Jack Dempsey, much larger for multiples.

Jack Dempsey Tank Mates : Try to keep them with fish of similar temperament (other Central American Cichlids). Watch for aggressiveness and remove or use an aquarium divider if necessary.

Jack Dempsey Disease : Freshwater Fish Disease - Diagnose, Symptoms and Treatment

Diet / Foods : Usually very good eaters, they will take flakes, pellets, freeze dried (blood worms, brine shrimp) and especially live foods.

Tank Region : Middle to bottom

Gender : Females may be smaller and less colorful.

Author : Mike FishLore

Fish Lore Forum : Jack Dempsey Cichlid Forum


Jack Dempsey Fish Tips

From: Jo
The Jack Dempsey is by far the best fish I've ever kept. Right now I have 1 5" female jack dempsey that lives with a common pleco. Though I'm thinking about getting a few convicts. I feed her tropical flakes with the occasional rosy red gold fish that she loves. She also loves worms and crickets, and rarely she'll eat the algae wafer I put in for the pleco. Another thing is, never keep it with something smaller than it (there are some exceptions) because they will kill it.

From: Darren
I got mine from my brother because they killed all the fish in his tank including a 12 inch pleco. The only way I have found is to give them a bigger tank, like 55 gallons or larger!

From: Michelle
I just got a jack dempsey and he is just a baby. Every time I feed him flakes he attackes them as if they were alive (lol). He is so cute!

From: Allison
We got our Jack Dempsey's (2) on a whim one day and they have been the most entertaining fish we have had. They surprised us (after a month of owning them) and now we have hundred's! We have other fish in the tank and they have been defending their young and have been doing a remarkable job of being parents! We are so happy to have the Jack Dempsey's and we will continue to care for them and possibly breeding them accordingly.

From: Tay
Hi, I went to a pet store today where I was told that Jack Dempseys do well in only a 20 gallon tank. Would this be true if it were the only fish in the tank? Also, I would like to get some Blue Rams to go along with it. Would these two fish be compatible? Any information would be greatly appreciated!
I would recommend that you NOT follow that advice. This fish gets way too big for a 20 gallon tank. The blue rams stay quite small for cichlids (2 inches maybe) and would make a nice snack for a full grown Jack Dempsey.

From: Tom
I have had Jack Dempseys since I was a kid. You can put them with other fish if you go with a large enough tank. Currently I have 1 large male with a Red Devil Cichlid of the same size, a Deboise about 4", 2 Jewels about 3" and some cats in a 120 gallon tank. They all look great, no fin nipping and only minor territory chasing. A good way to start is with a few aggressive fish all bought at the same time (young) and they will all fall in line. Currently the Jack and the devil swap dominance in the tank. They truly are a great fish to have.

From: Steve
I've had my fish for five years or more, recently bought a 77 gallon tank, and decided to do a little research on him. You see I have always known him as an "Oscar" until I saw the picture of a "Jack Dempsey" in your site, I couldn't believe it, "that's my fish". Thanks to your site I can now finally say "I have a Jack Dempsey", and he's in excellent health. By the way, 20 gallons is not enough, my poor guy was cramped up like that for a long time sad to say. It's a very expensive commitment to make, but to watch them glide around a large well lighted aquarium is well worth it.

From: Hardy
I had a jack dempsey for around three years, during which time I came home several times to find it had jumped out of the aquarium and landed the carpet. I have no way of knowing how long it had been out before I found it, but once I placed it back in the water each time, it was totally fine. So it's a pretty tough fish. Unfortunately it killed every other fish in my tank, including another (presumably male) dempsey. So I had a love/hate relationship with this fish. When I went away to college, it suddenly, mysteriously died.

From: Adam R.
The Jack Dempsey is a very beautiful and colorful fish. With the two I have, the female has grown to about 5" as the male has grown to around 8". The male seems to have more aggression then the smaller female. I have them in seperate tanks because the male was too aggressive for the community tank. He is with male convict cichlids and they do fine together. These fish need a minimum of a 55 gallon tank.

From: Denine
I love my jack! He's very aggressive and loves his live food. That is awesome that you can feed crickets and worms to them! My Jack watches everything I do. When he sees his food he wiggles around excitingly. When he wants my attention he'll jump out of the water to make a splashing noise and gets so excited. My friends can't believe it when they see it. They think it's a fish wanting to be a dog. So smart and very entertaining.

From: Utsav
I've had Jack D for about a year. They are very calm fish as far as my experience but they do not like strangers in their tank at all. I had tried keeping two Jack D (Male and Female) and two texas convicts. I never saw the convicts because they were constantly hiding. I am still waiting for them to grow to their full size, so best of luck to me.

From: Andrew Dasilva
I rescued my JD from my local university, after it was left just to "exist" after the animal behavior studies were completed with him. He was cramped in a 25 gallon tank, being over 8" long. He is now comfortable in a 55 gallon tank, all alone (Just like he was after he supposedly ate all of his friends five-to-eight years ago). He's old, and I hope to keep him happy for the rest of his life.

Is it just me or do Dempseys love caves? I have a huge PVC pipe elbow (6"), and that is his favorite spot.

The fish needs lots of filtration. Very messy eaters. Double the amount of filters typically needed for your tank (I have two Penguin 350's going).

The fish is very hardy though. When I first met him in his aquarium at the college, his water had a pH of 5.5, and 8 ppm of ammonia, and he was still looking pretty healthy. I couldn't recommend any other fish to spend money on.


From: Briana
We've had a Jack Dempsy for about 5 months now. He was a rescue from someone who was no longer caring for him or the tank. He is very agressive; I'm guessing because he had to eat his tank mates for lack of food. He is now in a 35 gallon tank by himself. He doesn't move around as much as he used to and his color has paled quit a bit. He is a very picky eater and will only take shrimp pellets. Any suggestions on how we can at least get his brilliant color back?
Yeah, a much larger tank with regular water changes and a varied diet to start.

From: Brandon's Mom
My son Brandon was always so compassionate towards and loved animals. So when he was about 16 he decided he wanted fish and he insisted on getting fish that that would grow to be pretty BIG. So he chose a male and female Jack Dempsy. It wasn't long before we had a bunch of fry or baby Dempsies. From those Babies, Brandon kept 4. Brandon died from Hypothermia on January 7, 2007 (3 months short of his 21st birthday). I brought the original pair of Dempsies home with me and my oldest son took the 4 babies home with him. Exactly 6 months after Brandon left us, on 7/7/07, two of the babies had babies. Now I have 3 of the newest babies, my 16 year old son has 6 of them, my 18 year old has 3 of them and my oldest son (the 25 year old) shares the rest of the babies with their Dad (they live in the same home now). It is sort of like we all have such a special part of Brandon now and hopefully, we will have many generations of Brandon's Dempsies to come (we all chose to take 3 or 3 + 3 because Brandon's Varsity Basketball number was 33). By the way, the original Dempsy couple are now about 6 and 8 inches long, the second generation are about 3 and 4 inches, and the newest babies are almost 1/2 to 3/4 of an inch now. I'm so happy Brandon left us with such a special gift.

From: Frank
Just wanted to let Brandon's mom know that her story was awesome. I have had my Dempsey since he was a baby and I love it to death. I have him in a 39 gallon hex tank with 1 black belt and 1 pleco. It's almost time to move up to a 75 gallon. The Dempsey is about 6 1/2 inches. I also started an additional tank with 3 blue dempsey's. They are all so much fun to watch.

From: Andrew Dasilva
I have an eight year old JD that I saved from my college. It was about eight or nine inches long in a 25 gallon tank :( It is now in a 55 gallon tank with two penguin 300 filters, a 100 gallon air pump, two reverse flow power heads, and weekly 10 percent water changes. The fish is such a messy eater! He only had Cichlid Sticks while living at the college, now he has those, the purple container cichlid pellets, hikari cichlid gold pellets, and freeze dried krill. He recognizes the package that the krill comes in because he is more determined in getting those as soon as he sees the package compared to the others.

He is also in love with one of my six cats. He will stay and watch it for hours and hours if it is in my room. He'll ignore eating or whatnot if the cat is in the room. I am glad he has such interaction, even if he is still a solitary fish. I am glad I am giving him a better home. Its just creepy some times how smart he is. He also loves to hide in his flower pot and PVC pipe elbow. he's so big, I had a hard time figuring out what to give him to hide in. He also uproots the fake plastic plants I set in there.


From: Max - Tank is too small
I was wondering how long could I keep a juvenile JD in a 20 gallon tank?
You need to get your JD into a much bigger tank as soon as possible. Keeping them in a smaller tank such as the 20 gallon can stunt its growth and shorten it's life span.

From: John D. - long lived Jack Dempsey
We have a JD that is now 19 years old he had a 80 gallon tank and 2 years ago I moved him into a 150 gallon tank. We feed him flakes and live food. 2 years ago I put 12 Gold Fish in his tank as food and he ate all but 1 of them. The 1 is still here today and we call him the JD's pet. A few months ago he developed a been in the middle which has not gone away and he is blind in 1 eye but we love him so much we cannot part with him. We know he will be gone soon but we hope not to soon.


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