Jack Dempsey Fish – A Complete Guide (Care, Diet, Facts)

Many people don’t think fish are exciting pets to keep, but they make excellent pets. Keeping fish is a rewarding hobby, and fish need less care than other types of pets. Fish are beautiful additions to any room.

Jack Dempsey fish are a popular kind of tropical freshwater fish. They are colorful and active, but they can also be territorial and aggressive.

Beginners can successfully keep Jack Dempsey fish, but there is a lot of important information to know before adding them to your aquarium. If you’re interested in keeping a Jack Dempsey, follow this guide so you can take good care of your new fish.


What Are Jack Dempsey Fish?

Jack Dempsey fish, also called Jacks, are part of the Cichlidae family. Cichlids are usually found in lakes and rivers in tropical parts of the world.

The Jack Dempsey is officially classified with the name Rocio octofasciata. This species is native to countries like Mexico, Honduras, and Guatemala. Jacks got their name from the famous boxing champion Jack Dempsey.

Jacks grow to be anywhere from 8 to 10 inches long. They have long oval bodies and fins, and they are very thin when you look at it face to face.

You can figure out the sex of your Jack Dempsey fish by looking at its fins. Male Jacks have long fins with pointed tips, and female fish have shorter fins.

There are a lot of color varieties of Jack Dempsey fish. Young fish are gray or tan with colored specks. Jacks become more colorful as they get older, and the most popular colors for Jack owners are gold, blue, and pink.

Jack Dempsey can also change colors for different reasons. Jacks become pale when they are stressed or unwell. Their color gets darker when they are ready to mate.

Jacks are omnivorous and aggressive fish. They typically live for 8-10 years, but they can become as old as 15 if they are kept in a good, healthy environment.

Jack Dempsey Habitat and Tank Conditions

It’s important to keep your fish in a tank that fits their needs. Jacks like to live in large freshwater tanks with an interesting setup.

How Big Should My Tank Be?

Jack Dempsey are big, territorial fish and need to be kept in big tanks. This might be surprising because young Jacks are only 2-3 inches long when you first purchase them!

You should keep your Jack Dempsey in a tank that’s at least 55 gallons. This is because they need room to grow, explore, and hide.

If you want to keep more than one Jack in the same tank, give each fish about 50 gallons of space. So, if you have three Jack Dempsey, get a 150-gallon tank.

How Do I Take Care of My Tank’s Water?

A lot of freshwater fish need very specific water conditions, but Jack Dempsey can thrive in a variety of different conditions.

The most important way to take care of your tank’s water is to monitor the temperature. Use an aquarium heater to keep the water between 78 and 82° Fahrenheit.

Jack Dempsey fish can thrive in a variety of water pH levels. Try to keep the pH range between 6.5 and 8.0.

Alkalinity and water hardness aren’t the most important levels to monitor, but they should both be around 5-12 degrees. Low alkalinity can drop the water’s pH, so change your tank’s water every month to maintain alkalinity and pH levels.

Remember to use a good water filter for your tank. Filters are important in big tanks to get the waste out of the water. If you’re not sure what size filter you should get, a good general rule is to go one size up.

Again, pay the most attention to your tank’s temperature, but take care to maintain pH, alkalinity, and water hardness levels.

How Should I Set Up My Tank?

Jack Dempsey are territorial fish. They like to have interesting decorations that they can explore and claim as their own.

Jacks are cichlids that dig in their tank’s substrate or gravel. Use a fine, sandy substrate that can level itself out after they’ve sifted through it looking for food.

Jack Dempsey like to explore their surroundings. Decorations like rocks, caves, and driftwood logs provide lots of places to hide and cover.

If you want to use live plants in your tank, pick a hardy plant that can survive in the tank’s 78 to 82° Fahrenheit range. Java moss is a great option for Jacks.

Jack Dempsey Behavior

Jack Dempsey fish can be very aggressive. Beginners often don’t have the skill or preparation to handle aggressive fish, so Jacks aren’t a good fit for beginning fish keepers.

Jacks tend to claim and hide in any caves or crevices in their tanks. They spend most of their time in the middle or bottom of the tank.

Can Jack Dempsey Fish Be Kept with Other Fish?

Even though Jack Dempsey are aggressive, they can still be kept with other fish species. Their tank mates should be about as big and aggressive as your Jack.

Smaller or more peaceful fish are more likely to be targeted or attacked by Jack Dempsey fish. Tetras and tropical invertebrates will probably be treated like food.

Other cichlids the same size as your Jack are the best tank mate options. Common picks are Angelfish, Blue Acara, and Oscar fish.

Can Jack Dempsey Fish Be Kept Together?

Keeping multiple Jacks in the same tank is easier than housing multiple species in the same tank. Jacks are less likely to be aggressive towards each other because of their similar aggression levels.

However, male Jack Dempsey don’t get along very well with other males. If you’re considering keeping more than one Jack in the same tank, check the sex of your fish before putting them together.

Feeding Your Jack Dempsey Fish

Jack Dempsey fish are carnivorous fish that prefer meaty foods. There are a lot of options, so choose a diet for your Jacks that works for you.

Jacks prefer live foods over dried or processed options. Dried foods are cheaper and easier to find in stores, but they don’t provide very many nutrients.

On the other hand, meaty foods like shrimp or insects are harder to find and store at home. Jack Dempsey prefer this diet, though, so it’s worth it to invest in live foods. You can usually find fresh or frozen varieties.

Cichlid and carnivore pellets are some of the most popular options. If you feed your Jack Dempsey dried pellets or flakes, be sure to add other live options to the tank occasionally.

Good meaty foods for your Jack include worms, crustaceans, and even small fish. Brine, shrimp, and bloodworms are the most common frozen foods you can find. Insects like fruit flies and crickets are also favorites.

Jacks will typically reject plant-based foods. This should not be a problem if you have access to good carnivore options.

Adult Jack Dempsey should be fed once or twice a day. However, younger fish need to be fed two or three times per day to help them grow.

Only feed your fish what they will finish eating within one or two minutes, and take whatever they don’t eat out of the tank. Unfinished food can pollute your tank’s water and harm your fish.

Breeding Jack Dempsey Fish

You can breed Jack Dempsey fish yourself, but this will require handling your fish when they are more aggressive than usual. Be prepared to remove fish from the tank if breeding attempts aren’t successful.

Keep your water in perfect condition to get ready for breeding. The water should be clean and within the specified pH, water hardness, and alkalinity levels outlined earlier. Increasing the temperature to around 84° can trigger the breeding process.

Jack Dempsey can also harass other fish that aren’t in the breeding pair during the breeding process. Take the other fish out of your tank before the pair gets too violent.

When Jacks are ready to breed, their usual colors will get darker. Both the male and the female need to be ready at the same time. The male fish can bully or attack the female if she isn’t ready.

Jacks can lay eggs on any flat surface in the tank like decorations or the walls of the tank. You can also provide a flat stone for the Jack Dempsey to use. The fish will clean the stone and pick at it to prepare it for eggs.

After mating happens, the female fish can lay up to 500 eggs. The eggs should hatch in about three days, and the fry will become free-swimming in ten days.

The parents take care of the young when kept in good conditions. They will take turns guarding the eggs and the fry. They will also crush up food for the young fish before they can find food on their own.

Maintain your tank’s environment during this time to avoid distressing your Jacks. If they get stressed, they might start to eat the young. Separate the parents from the fry if it begins to happen.

Common Jack Dempsey Care Problems

Is your fish not doing well? Here are some common problems and solutions if you can’t figure out how to take care of your Jack Dempsey.

My Jack Dempsey Fish Is Attacking Its Tank Mates

Jack Dempsey are large, aggressive fish. They will attack and harass tank mates that are smaller or try to eat them.

Separate your smaller fish from your Jack. Only house your Jack Dempsey with fish that are similar in size and aggression.

Jacks can also attack each other. This is most common when you have two male Jack Dempsey in the same tank. If you have more than one, keep them in different tanks.

My Jack Dempsey Fish Isn’t Eating

Jack Dempsey are carnivores. They will only eat meaty foods, so check to see if the pellets or flakes you’re using are plant-based.

Feed your Jack a varied diet. If you only feed them dried foods, they won’t get the nutrients they need. Mix it up with some fresh or frozen options.

How often are you feeding your Jack Dempsey? Adult Jacks should be fed once or twice a day, and younger fish need to be fed two or three times every day.

If you feed your fish more often, you might be over-feeding them. Watch to see how much food your Jack Dempsey eats and only give them what they can consume in one or two minutes.

Not eating is a sign that your fish could be sick. Keep a close eye on your Jack’s behavior and talk to a vet to evaluate them.

Is My Jack Dempsey Fish Sick?

Your fish might be behaving strangely for different reasons. They could be stressed from their environment or developed an illness from poor tank conditions or a bad environment. Clean your tank often.

Jacks need to eat a meaty diet to stay healthy. Make sure your fish is getting enough phosphorus, calcium, Vitamin D, and Vitamin C to avoid “hole-in-the-head” disease.

Ich is another common illness for freshwater aquarium fish like Jack Dempsey. You can spot Ich if your fish has white spots on the gills and body.

Treat this sickness by raising your tank’s temperature to 86° Fahrenheit for a day or two. Jacks are hardy fish that can tolerate higher temperatures for a short period of time, and the increased temperature will kill the infection.

It’s never a bad idea to talk to a vet if you’re worried about your Jack Dempsey. These common problems can be solved at home, but ask your vet if your Jack needs more specific treatment.

Is A Jack Dempsey Fish Right for You?

The best way to care for your Jack Dempsey fish is to keep its tank clean and at the right temperature. Don’t overfeed your fish.

A Jack Dempsey is a good fit for you if you have experience caring for aggressive fish and you have a big tank to keep it in. Jacks might not be the best fish for you if you are new to keeping fish, don’t have a big tank, or only have smaller fish that a Jack could target.

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