Jack Dempsey Fish: How it Got its Name, Care Guide and More!

There are thousands of different fish you can opt for putting in your aquarium, but the truth is that not every fish is a good fit for every tank, nor for every tank owner. The Jack Dempsey fish is an interesting looking fish species that you will find in North America and Central America in particular, but it is popular in aquarium tanks all over the world.

When it comes to some species not being a good fit for everyone – the Jack Dempsey Cichlid is a great example, so here is a guide to help you see if an electric blue Jack Dempsey is the right fish for your tank.

About the Jack Dempsey Fish

Before you can figure out if this fish is a good fit for your aquarium, you need to gain a basic understanding of what this fish is; how it acts, what it does and what it requires in order to thrive and stay healthy, as well as what kind of an aquarium is right for this bad boy of a fish.

The Jack Dempsey (fish), also known by its scientific name Rocio octofasciata, is a species belonging to the Cichlidae family. It is native to particularly Honduras and southern Mexico, but you will also find it in the United States, Australia, and Thailand, where it has been deliberately introduced and now forms part of the ecosystem. Having Jack Dempsey Cichlids in your aquarium can be great, but you need to know what you are in for, both to ensure that your Jack Dempsey thrives, but also that the Jack Dempsey tank mates are compatible. Here are some basic Jack Dempsey facts:

Information Chart
Care Level:
Dark purple-grey with colorful flecks; color changing
8-10 years
10 -15 inches
Minimum Tank Size:

55 gallons+(ideally 80 gallons)

72-86 ºF (22-30 ºC)
Water Conditions:
9-20 dGH water hardness / PH between 7.0 and 7.5
Tank Mate Compatibility
Fish of similar size and with similar personalities

The Jack Dempsey naturally lives in still and swamp-like waters – often with plenty of weed and muddy or sandy river bottoms. The tank will have to be conditioned to mimic the tropical conditions the Jack Dempsey is used to living in, and you will also have to pay special attention to any future Jack Dempsey fish tank mates you might already have in the tank. The Jack Dempsey fish lifespan is approximately 8-10 years.

Different Types of Jack Dempsey

Jack Dempsey in tank water with another fish

The species is called Rocio octofasciata, and there is only one type of this feisty little swimmer, but there are multiple different colors you are likely to come in contact with if you choose to add a Jack Dempsey fish to the tank. There is a pink Jack Dempsey, an electric pink Jack Dempsey, platinum Jack Dempsey, and yellow Jack Dempsey, and there is even the chance of an Albino Jack Dempsey! There are all the same species, and only their physical appearance in terms of color can vary somewhat. The electric blue Jack Dempsey is known for being somewhat less aggressive, and also smaller in size.

The color of a Jack Dempsey fish can change an vary depending on its mood, almost like one of those mood rings that were temporarily popular in the late 90s, and stress and age are two of the things that can invoke these sudden changes in color.

The Fish and Its Behavior

Beginners are often surprised by the seemingly aggressive nature of the grayish-blue Jack Dempsey, and it is not unusual that you end up regretting your decision to make one a part of your tank. This is more a result of you as a tank owner being unprepared, rather than the fish being unfit to live in harmony in an aquarium. Jack Dempseys can come across as aggressive when in reality a better term would be ‘territorial’. It tends to stay in the back or middle of the tank, where it will defend its turf with everything it has got.

This does not mean that it cannot live with other fish, and it generally does well with other Jack Demsey cichlid tank mates, surprisingly enough, or in a tank that is well populated. The reason for this is that the Jack Dempsey often takes on a bully-like role, and they may single out fish that keep to themselves, something that doesn’t happen as often if there is plenty of fish living in the aquarium. Providing the tank inhabitants with many different hide-outs and caves can also help reduce its territorial behavior, as each fish will have somewhere to go without imposing on any of the others.

Jack Dempsey Cichlid Care

Jack Dempsey Cichlid in Aquarium

Know let’s talk about Jack Dempsey care. You don’t have to be an expert to make a good Jack Dempsey fish owner, because while it can look a little hard and rough (just like the 1920s boxer it is named after) – it can also be quite a charmer! In terms of care, there isn’t much you need to do other than to make sure it does not bully other fish.

The ectoparasite Ich, also known as White Spot Disease, is one of the health conditions the Jack Dempsey fish is known for sometimes battling with, but other than that – it is considered a healthy species that is fairly easy to care for, especially if you have had aggressive fish species in the tank previously. If you have had fish with aggressive behaviors, you will be ready for what is to come, and you are therefore more likely to succeed in your Jack Dempsey ownership.

When successfully cared for and kept, this is a fish that will be around for a long time, with an impressive lifespan of 8-10 years – quite long considering its size (the average size is 10-15 inches for a fully grown Jack Dempsy fish, but the females are usually slightly smaller than the males), and it will add a fantastic dash of glimmering color in your aquarium water.

Jack Dempsey Cichlid Breeding

A clear sign that both the female and the male are ready for mating is that their color grows significantly darker, and then it is all about timing – both need to be ready at the same time, as an unwilling female fish could even get killed. The best way you can help the process is by making sure the tank is properly conditioned, with the correct water temperature, and the water should be kept clean and fresh. If you try to keep it closer to the upper-temperature recommendation rather than closer to the lower, then your Jack Dempseys are more likely to get in the mood.

Cichlids will often have an easier time pursuing a female if they are on the larger side, and the Jack Dempsey is no exception. If everything goes well, your colorful fish could end up having approximately 500 eggs that hatch after somewhere around 3 days, and they stick to all types of flat surfaces inside the aquarium.

An interesting thing about the way the Jack Dempsey mate is that the female fish and the male fish both share responsibilities for the babies once they are hatched, and they stay close to them to keep them safe from other species in the tank. Make sure you have provided the pair with a suitable place for them to have their babies, such as a nicely sized cave, and be responsible when you breed.  

Conditioning the Tank

There is a very simple way of figuring out how to condition a tank for a Jack Dempsy fish, and it is something that works well no matter what kind of fish you plan to acquire. Always consider the natural living conditions of the fish, such as – in this case – the Dempsey fish coming from a tropical and warm climate with water full of weed and natural hiding places.

Try your best to recreate these conditions inside the aquarium and/or tank, by
providing appropriate plants, caves, other hiding places and by keeping the water temperature just right. Jack Dempseys can appear shy as they always seem to be hiding, but they can be quite sociable when they want to be, as long as they have that hidden away space to retreat to whenever needed.

Appropriate Diet for a Jack Dempsey

Are you worried about what your full grown Jack Dempsey will eat? Don’t be. They are carnivores, meaning they feed on meat, but most Jack Dempseys will eat pretty much any type of meat or meat-like thing provided it can fit in their mouths. To add some extra protein to their diet, you can always consider adding bloodworms a couple of times a week, as they are going to love it, as well as benefit greatly from the nutrients found in these worms.

An adult Jack Dempsey tends to need to eat a couple of times a day, but don’t waste your time trying to convince them to eat plant-based food, as this will likely not be popular. The plus here is that you generally don’t have to worry about your new fish munching on your tank plants!

Choosing Tank Mates for a Jack

One thing to keep in mind is that it usually isn’t a great idea to just let a Jack Dempsey fish into an already set up aquarium, without first considering the likelihood of it getting along with the fish already in there. Jack Dempseys have a habit of singling out lonely and exposed fish, so the smartest thing you can do is to choose tank mates that are similarly sized and have a tough personality, just like the Jack Dempsey.

It usually gets along well with other Jack Dempseys, as well as other Cichlids, Angel fishCascarudoRasboras and more, so try to do a little research on the subject before you make your final decision. Species from the Synodotis family are usually also a good mix, as well as Loricariidae family species, Silver Dollar fish and Tinfoil Barbs. 

For those wondering whether it gets along with, for example, an Oscar, the answer is surprisingly yes! With both being aggressive fish species, it may seem like they wouldn’t get along, but they can actually make great tank mates if you condition your tank with multiple caves and more.

It is easy to think that an aggressive fish like the Jack Dempsey might benefit from a less crowded tank, but that would leave more fish alone and exposed, often making it a better call to fill your tank up a little (reasonably), so that the Jack Dempsey becomes part of a small crowd. 

As previously mentioned, it is recommended that you provide your fish with enough hiding places for everyone, as the Jack Dempsey is less likely to fight if nobody tries to enter its territory or claim its cave or space. If you remain unsure
of which tank mates to choose, a knowledgeable employee at your local pet store may be able to help you choose.


Now that you know more about this remarkable fish species, it will be much easier to decide if it is right for you, but also how to properly condition a fish tank. It may not be a great fish for someone who is just starting out, but if this is something you are interested in, proper preparation and conditioning makes anything possible. 

The Jack Dempsey fish has a great and colorful personality, which weighs up for its aggressiveness, and for someone with a bit of experience or a will to learn – it is not a difficult fish to maintain. The Jack Dempsey fish price will depend on where you are located and what your options are. 

In the United States, the average price is usually somewhere between $10 and $15, and it will give you a colorful fish to keep in your aquarium for years to come if cared for correctly. Take a chance on this feisty fish and let it surprise you with its personality that can sometimes seem to be larger than life.

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