Jack Dempsey Fish – Species Profile & Facts

Jack Dempseys are one of the most well-known cichlid fish species. You will find them in many home aquariums, which is mainly due to their attractive appearance.

They have mostly a black or dark body with glittering blue scales or spots all over their body. They are among the cichlid family, which contains more than 1500 other fish species that are relatively similar.

You might be wondering about the name of this fish – it sounds like a person, doesn’t it?

Well that’s because this fish has been named after Jack Dempsey, the former world heavyweight boxing champion from 1919 to 1926. This boxer was known by his ruthless attacks in the boxing ring.

And this fish was named after the boxer exactly because they often show a similar type of behavior in the fish tank.

They are aggressive fish and can mount similar attacks on other fish in your aquarium. While they are not the best community tank fish, they are still a very popular species that many fish tank owners love.

With their attractive appearance and interesting behavior, they certainly present an interesting fish for fish owners. They might not be the best fish for beginners, though.

In this article, we’ll take a closer look at this species, and how you can easily keep this fish in your aquarium.

Jack Dempsey Natural Habitat

Most Jack Dempsey fish will be found all across North and Central America. There are most of these fish in Honduras and Mexico, but have spread very quickly over other countries in Central and North America, as well as South America.

You’ll also find them in hot waters of Australia and Thailand. These fish are most commonly found in slow-moving waters that are shallow, and where temperatures are very high (between 72 and 86 degrees Fahrenheit).

Lower oxygen conditions are also a general common fixture where these fish live, but they are also very adaptable as to where they can live.

That makes them a hardy and sturdy fish to own. They like natural caves and rocks very much, as they will have more hiding spaces and where the water can slow down.

This is the sort of areas they like. Make sure you have slow-moving water in your tank, too.

Jack Dempseys are carnivores, and they are very likely to hunt on other smaller fish in the tank or other smaller creatures they might come across. Worms, small crustaceans, and snails are very commonly found in their diet.

Jack Dempsey Fish Tank Requirements

The Jack Dempsey fish will grow to between 10 to 15 inches in size. When they are juvenile, they can be only 2-3 inches in size, which might mislead some fish owners, especially beginners.

That might lead them to buy 10 or 20-gallon tanks; but once these fish grow, they will struggle to survive as they don’t have enough space in their tanks.

It’s better to buy a larger tank of at least 55 gallons for a single fish from the start. This will allow them to grow fully, but it will also give them enough space to fully develop and live healthily.

However, if you intend to keep several fish in the tank, then you will need a much larger tank – 120 gallons or even larger, depending on how many fish you want to have.

As for the substrate, opt for a sandy substrate that is relatively soft. These fish like to spend their time near the bottom of the tank, and sandy substrate is the best guarantee that they don’t get hurt.

A heater will also be required, most likely, as it will be hard to maintain high temperatures for many fish tank owners.

You can add plants, too, but be mindful, as these fish can sometimes destroy the plants if they don’t like them.

Since these fish prefer a slower moving water, you might need a filter with an adjustable flow rate so that you don’t overwhelm these fish with the water flow.

Jack Dempsey Water Conditions

As we have already suggested, you will need to make sure that the water temperatures stay between 72 and 86 degrees Fahrenheit at all times.

Jack Dempsey fish can be adaptable and will adapt to lower temperatures, but you shouldn’t expose them to lower temperatures for longer periods. A good water heater will come handy for most fish tank owners.

These fish prefer a neutral PH, so try to keep it between 6.5 and 8. As for water hardness, this is not a crucial demanding factor, but it’s something you also need to keep in mind when you own these fish.

It should, ideally, be between 5 and 12 DGH. Make sure you check up on it every now and then and make sure it’s in the preferred levels.

Chronic exposure to ammonia and nitrites will put your Jack Dempsey fish at the risk of diseases, which can also be fatal.

In that case, you will need to cycle your water often and make sure it’s as clean as possible in the long-term.

Good water care and maintenance is necessary, as is having a good filtration system in place. It must be said that these fish are very vulnerable to high levels of pollutants, so try to keep them as low as possible at all times.

Jack Dempsey Diet and Feeding

Jack Dempsey fish is a carnivorous fish. Their diet, or the majority of it, should consist of meaty foods that are full of protein, and that they fit in their mouth.

The best foods for these fish are worms, crustaceans, insects and smaller fish, which is what they also tend to eat in the wild.

But these foods will not always be available to you, and you should keep a good variety in their diet.

Consider dried foods, which are more readily available and are often also much cheaper. Consider adding pellets or flakes to their diet, and choose pellets or flakes that are especially designed for cichlids.

You can try to add herbivorous foods, but don’t expect these foods to be welcomed by the fish. They will, most likely, refuse to eat such foods, which is why you should try to keep a meaty diet instead.

As for the feeding windows, I recommend that you feed the fish 1-2 times per day with relatively larger meals.

Make sure the fish can consume the foods you give them in two minutes or less. For juveniles, they should be fed much more frequently – 2-5 times per day seems to work best.

Jack Dempsey Tank Mates

Jack Dempsey fish are not the best community tank fish. They are aggressive fish, especially if they don’t have enough space in the tank.

That does restrict the choice for tank mates somewhat, although it doesn’t necessarily mean that there are no tank mates available for these fish.

If you want to pick the best tank mate for this fish, opt for fish that are similar in size and have a similar temperament to them.

Smaller or larger fish should be avoided, but especially smaller fish, as Jack Dempseys will actively prey on them and consume them.

Don’t consider peaceful fish, too, as they will be most likely harassed, and in some cases, even to death. So you should make sure the other fish in the tank should be able to defend themselves against the attacks of this fish species.

Here are some fish you can consider:

  • Oscar fish
  • Angelfish
  • Birchir
  • Blue acara
  • Clown loaches
  • Convict cichlids
  • Firemouth cichlids
  • Plecostomus
  • Silver dollars.

You can also consider a species-only tank, where you keep one male and a female or several females.

That’s the best option for beginners, although do make sure that the females get enough space in the tank so that they can safely flee or hide from the males when they chase them.

Jack Dempsey Breeding

Breeding these fish is possible, although they will need precise and exact water conditions to initiate the breeding.

The problem might happen when the male is ready for breeding while the female isn’t – that’s when you can expect the male to harass the female, sometimes even to the point of death.

That’s why you should try to keep temperatures much higher when you want to breed them – around 84 degrees Fahrenheit seems to be a good estimate.

Both male and female will turn darker when they are ready to breed. Larger males will usually be more successful in catching the female for breeding.

When these fish mate, 500 eggs are produced. Then, they attach the eggs to a nearby surface, and the female will actively protect the eggs.


Are Jack Dempseys the right option for your tank? If you’re looking for an attractive fish in terms of looks, then yes.

However, be mindful that these fish can be aggressive towards other fish, especially towards smaller fish.

Some precautions need to be taken in order to keep this fish. This article has told you all about those precautions and hopefully, you can now keep these fish in your tank.

avatar Noah
I’m Noah, chief editor at VIVO Pets and the proud owner of a playful, energetic husky (Max). I’ve been a volunteer at Rex Animal Rescue for over 2 years. I love learning and writing about different animals that can be kept as pets. read more...

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