The Jack Dempsey Fish (Rocio octofasciata) is from the Cichlid family and is extremely popular among Cichlid enthusiasts. Colorful and vibrant as they age and are conditioned over time, they make for a rewarding species to care for.
They might not be for everyone (if you’re looking for a docile and calm fish to incorporate into a peaceful community), but for those more experienced keepers, they are a Cichlid many keep on coming back to.
While known for aggressive behaviors, they are still a species that will suit group living amongst others. You just really need to know who they can manage to live alongside well with to avoid too many interspecies or, indeed, fellow specimens issues.
These fish are usually found in the wild in slow-moving waters of North and Central America, particularly Mexico, Honduras, and neighboring countries. They have also been introduced and are now established in areas of Thailand and Australia.
These medium-sized fish make excellent active, boisterous members of tank communities as long as you know what you’re doing with them.
What’s up with their name? Their common name is an ode to a legendary World champion heavyweight boxer from the 1920s by the name of Jack Dempsey. This was probably a result of their aggressive nature for pioneers of the fish-keeping hobby back in the day when it got its nickname.
We will delve a little deeper into these fish and how to best care for them in the modern era and see if they still pack a punch.
Jack Dempsey Fish Behavior
Although known as a relentlessly aggressive fish in the fish-keeping sphere by word of mouth, the reality is that they aren’t as aggressive as perhaps they once were.
Some say they don’t make great tank mates, but it is very much possible to house them with others if you know what you’re doing.
Known to get more territorial with age, these fish can harass, bully, and even kill other fish if they think their turf is being encroached upon.
They prefer to stake a claim to some area of the tank that offers cover and retreat.
Active and interesting to observe, these fish prefer the middle to bottom layers on the tank sphere.
If you plan on having a mating pair, you will need to separate them from the rest of the community during the breeding season. Without exception, they will punish and try to eliminate anything else that is in their path while mating and rearing their young.
The key to keeping aggression manageable is to house them with other similarly aggressive Cichlids who can hold their own. This doesn’t mean there won’t be squabbles and inevitable injury, but you, as the hobbyist, need to be prepared to deal with such scenarios.
Interestingly, when first introduced to a tank, these fish can come across as remarkably shy. Don’t be fooled! It won’t take long for them to establish their base and then defend it tirelessly against the rest of your tank world.
Ensure you have enough retreat areas for all of your fish so that there is less competition for territory, and this will help reduce aggression for the community. If it starts to become overcrowded, aggression will ramp up and end with a disharmonious vibe sure to end in tears.
Jack Dempsey Fish Lifespan
The Jack Dempsey fish can usually survive 8-10 years on average but have been known to survive years longer if kept in the right conditions.
This means that you are looking at a longer-term commitment than much smaller, docile fish, and this needs to be taken into account.
We will discuss more on tank requirements a little later in this article.
Jack Dempsey Fish Appearance
Available in a wide variety of coloration patterns, the Jack Dempsey fish is widely used to brighten up and inject life into the tanks of hobbyists.
Provided you can supply them with the right community and setup, they make an outstanding addition to your tank visually, which is why they are so popular.
Their bodies are oval and have a variety of skull shapes depending on breeding and certain color patterns. The body shape is also fairly wide, and therefore they are not a ‘slim’ fish and create a lot of waste compared to, say, and Angelfish.
They have large, long dorsal fins that run the length of the body and similarly shaped anal fins that are long and run along almost the full length of their underside. A large, classic fan-shaped caudal fin rounds off the shape of this fish.
They can get up to 10 inches in length, sometimes more, but on average, they are more likely to be 6-8 inches. It’s all about the tank size. Males are a little bit larger than females.
These fish can be found in base colors like dark, rosy pink to grey, and black. On top, their scales are metallic and iridescent that are often blue/green. Their coloring develops as they age and is also dependent on their care level and attention to detail.
Some of the most popular colors are pink, blue, and gold, but the scale flecking can vary from green to purple to blue/green. They truly are a rainbow!
Many hobbyists pride themselves on having flashy coloring as a result of their top-notch care that reflects their level of skill.
They are showy, center-stage fish which attract a lot of attention when anyone visits your tank and are bound to generate a lot of questions out of interest.
Here we should mention that there is a variant known as the Electric Blue Jack Dempsey.
These fish are costly and were created as a hybrid. They are electric blue, as you would expect, with a silvery-white body base color and long flowing fins. They are vibrant as juveniles through to the end of their lives and are prized for not needing the conditioning a standard Dempsey requires.
Jack Dempsey Fish Habitat And Tank Requirements
We know these fish are naturally found in slow-moving waters typical of swamps, river basins, smaller lakes, and lazier rivers that meander.
These large, carnivorous fish require plenty of space to thrive.
These tropical climate fish are hardier than many counterparts, which adds to their appeal. They can handle exceptionally warm waters, and you will need a heater to keep the temperatures suitably high.
Let’s take a look at the specifics for keeping your Jack Dempsey’s in fabulous condition and for keeping them happy.
Tank Conditions
These lower half of the tank-dwelling fish prefer a muddy, sandy substrate that can contain gravel or grit.
If you aren’t aware of this already, Cichlids are prolific diggers and root around in the substrate on a regular basis, so avoid planted vegetation unless you want to be rearranging and replanting often!
Keeps the substrate at least 2 inches in depth to satisfy their digging behavior and be prepared to rake it out and redistribute if necessary.
They need hiding places like caves, driftwood, rocks, and tough live plants or floating plants that offer cover. Great plants to try include Eel Grass, Water Sprite, Java Moss, Hornwort, Water Lettuce, and Anubias.
However, be sure to keep areas for open swimming as these fish are extremely active and like to patrol.
Filtration should be thorough and powerful such as a canister type, external filters, and add an extra sponge filter. Filtration is never too much for these big guys! They need zero nitrites and ammonia, so your planning for filtration is essential.
Water changes will need to be done each week with at least 30% per change.
Water conditions should be noted, tested regularly, and maintained as follows:
- pH of 6.0 – 8.0
- 3 – 8 GH
- 4 – 6 KH
- Temperature between 72 – 86ºF (22 – 30ºC)
- Nitrates < 40ppm
- Lighting can be LED-based but dim to appear like deep water
Tank Size
The minimum tank size needed is 55 gallons for a single Jack Dempsey. Ideally, you would be better off at a starting size of 80 gallons for a single and then add to the size for additional specimens.
For each further fish, you will need to add 55 gallons to keep the peace.
Choosing Tank Mates For Jack Dempsey fish
While we recommend choosing to keep your Dempsey fish how you wish, either solo or in a community, special care must be taken when choosing who to keep them with.
These are quite large fish that can inflict a lot of damage on anything too small or passive.
Here are your best bets if you are taking on Jack Dempsey’s into your tank:
- Green Terrors
- Firemouth Cichlids
- Severums
- Oscar Fish
- Angelfish
- Plecos
- Silver Dollars
- Clown Loaches
- Blue Acara
- Convict Cichlids
- Bichir
You will want to avoid any shrimp and most snails as they will be hunted down like prey and eaten.
It goes without saying that smaller fish will also be eyed up as a meal and should never be included in a tank with Jack Dempsey’s.
Jack Dempsey Fish Common Health Issues
Being a hardy species, Dempsey’s don’t have any special requirements when it comes to their health besides the obvious excellent water quality and condition.
Ich or White Spot Disease is also known as a freshwater parasitic infection that presents as white spots on the body, fins, and gills.
Head and Lateral Line Erosion is another thing to keep an eye out for. It presents as pitting around the head area before the operculum. This is a dietary issue, and you should rethink the quality of what you are feeding your Dempsey’s or add more variety.
Other than that, be observant of any unusual behaviors or manner of swimming. Ensure that their feeding is consistent and they are getting adequate nutrition.
Jack Dempsey’s are all about condition, condition, condition! They will visually reflect how well you have been taking care of their needs, so if they look vibrant and energetic, you’re doing a great job.
How To Breed Jack Dempsey Fish
Breeding Cichlids such as the Jack Dempsey is easier when you have just a pair in a tank that has already been sexed and are getting along.
If you haven’t got that, then you’ll need to separate them from others, or else the rest of your community is in peril.
These fish are an egg-depositing species. Ideally, if you are introducing a female to a male, he will try to spawn immediately, which will terrify the female, so get a barrier so she can be protected while preparing to spawn.
Once they do pair, however, you can expect them to mate for life and cohabit quite happily beside the odd knock and dispute.
The female will choose to spawn on a base that is under some cover, up to 500 eggs. The male will fertilize the eggs in the little pit they will have dug around the eggs to conceal them, and the fry will hatch shortly in around three days.
The mating pair are quite involved in caring for the fry and will protect them until they are free-swimming.
As always, the fry are susceptible to being consumed by their parents at any stage, so once they are free-swimming, they can be separated to protect them.
Remember we said they pair for life? Spawning will occur continually, and you will have to cull numbers or be able to reliably sell them. And it’s important to state here that they are not easy to sell because they grow rapidly, and housing juveniles requires a lot of tank space.
Conclusion
If you don’t already have an established Cichlid tank, your best bet for starting up with these fish is a tank just for them.
If you aren’t prepared to deal with an aggressive fish, then these aren’t for you.
But, if you are looking for something flashy, brilliant, with a lot of personality and action that make them a real conversation starter, then Jack Dempsey’s might be a gateway Cichlid for your hobby.
Be prepared to want more than one!
