The ideal tank size for Jack Dempsey fish depends on the number of fish in the tank. The average size of a Jack Dempsey fish is around 10 inches in captivity. Considering this, a minimum of 80-gallon tank is needed for a single adult fish, with an extra 50 gallons of water for every additional fish.
Apart from the size of the fish, numerous other factors also determine the tank size of Jack Dempsey fish. Let’s learn about them.
Minimum Tank Size For Jack Dempsey Fish
Jack Dempsey fish grow up to 15 inches in length in their natural environment.
In captivity, the average size of a male Jack Dempsey fish is around 10 inches.
Females are a bit smaller compared to males. They grow only up to 8 inches in length.
Since these fish can grow pretty large, you need a minimum tank of 80 gallons to house a single adult Jack Dempsey fish.
You can keep the young ones in a 55-gallon tank until they mature fully.
Another point to note is that at least 50 gallons of extra water is recommended for every additional fish.
A bigger tank is always better when housing large fish species like Jack Dempsey fish.
Recommended Tank Size For Jack Dempsey Fish
The optimum tank size for Jack Dempsey fish is about 100 gallons.
Since they’re large compared to some of the other freshwater aquarium fish, they need a lot of space inside the aquarium.
It’s best to recreate their natural habitat conditions in the aquarium for optimal growth.
They will thrive if you provide aquatic plants and ample hiding places in the form of caves, hollow decorations, etc.
The tank should also have enough room for them to swim freely without bumping into other tankmates and decorations.
A bigger tank is also beneficial as it’s more stable, has fewer temperature fluctuations, and is easier to maintain.
5 Factors To Consider For Determining The Ideal Tank Size For Jack Dempsey Fish
Setting up an aquarium can be challenging for a novice aquarist.
You must consider a lot of factors before buying a tank for Jack Dempsey fish.
Given below are some of the factors that you need to consider while deciding on the right tank size for your Jack Dempsey fish.
1. Number of Fish
The number of Jack Dempsey fish in the tank determines the tank size.
If you wish to keep a large group of fish, you must buy a bigger tank.
However, a smaller tank is sufficient to house a pair or small group of Jack Dempsey fish.
These fish are highly territorial toward other fish while defending their territory.
So it’s crucial that the tank must be large enough to hold all the fish comfortably.
2. Size of the Fish
The size of the fish is another factor when deciding the tank size.
As Jack Dempsey fish are large, they need a bigger tank than other smaller fish such as guppies, tetras, etc.
A tank of at least 80 gallons is required to house one Jack Dempsey fish.
3. Tankmates
Jack Dempsey fish aren’t ideal for a community tank due to their aggressive nature.
They’re unwilling to share their space with fellow tankmates and can become aggressive if their territory gets invaded.
However, some aquarists have successfully housed Jack Dempsey fish in a community tank.
To do this, you should carefully choose a tank that has sufficient space to accommodate all the tank inhabitants.
A large tank that allows all fish to claim their territory can help avoid territorial aggression and conflicts.
4. Tank Maintenance

Jack Dempsey fish need clean water to thrive.
They’re sensitive to pH instability and contaminated water. Hence, the tank must be well-maintained.
A larger tank is easy to maintain than a smaller one. The water parameters also remain more stable in a large tank.
Tank maintenance is tedious and can consume a lot of time.
So investing in a large tank is better, mainly when you can’t devote much time to maintaining the tank.
5. Essential Equipment And Decorations
You can’t keep Jack Dempsey fish in a barebones tank.
The tank needs to have essential equipment for them to thrive, such as a filter, heater, thermometer, aquarium lights, etc.
Even vegetation is vital in a Jack Dempsey fish tank. These fish like to hide.
So you need to provide ample hiding spots for them to feel secure.
Hiding spots such as caves, plants, castles, hollow decorations, etc., can make Jack Dempsey fish feel comfortable.
All these decorations and equipment take up space in the tank.
However, installing these essential things shouldn’t cramp the fish for space.
You need to consider all these factors before finalizing the tank size.
Can Jack Dempsey Fish Live In A 40-Gallon Tank?
It’s not recommended to keep Jack Dempsey fish in a 40-gallon tank. These fish need a minimum tank size of 80 gallons.
Jack Dempsey can grow pretty large, up to 10 inches in captivity.
Their large size combined with aggressive behavior means that they need ample space in the tank to move around.
A 40-gallon tank is way too small for these fish. You can’t provide adequate hiding spots for them in a small tank.
Jack Dempsey fish can also get stressed if they’re cramped for space.
What Happens If You Keep Jack Dempsey Fish In A Small Tank?
Like some cichlids, Jack Dempsey fish need ample space to grow to their fullest.
Keeping them in a small tank can stunt their growth significantly.
These fish can’t reach their full size when housed in a small tank.
They can even face other health issues like spinal deformities that can prove fatal and shorten their lifespan.
Jack Dempsey fish are territorial and don’t like to share their space with fellow tankmates.
So keeping them in a small tank can trigger territorial fights if other fish invade their territory.
Jack Dempsey fish can also get stressed if they’re cramped for space.
Another disadvantage of keeping Jack Dempsey fish in a small tank is that they won’t get enough oxygen due to the lack of space.
This can lead to respiratory problems.
Moreover, cramping fish in a small tank can affect the water quality as fish expel waste that creates ammonia and contaminates the water quickly.
If the tank water isn’t changed frequently, it can create havoc and deteriorate the health of all fish by causing bacterial infections.
Jack Dempsey fish also need sufficient space in the tank to explore their surroundings.
They love hiding places which can be difficult to create in a small tank.
Ideal Tank Size For Electric Blue Jack Dempsey Cichlids
The Electric Blue Jack Dempsey cichlids are one of the most recent and exciting genetic mutations of the Jack Dempsey Central American cichlids.
These fish stand out due to their bright blue coloration and striking pattern.
The Electric Blue Jack Dempsey fish are small compared to the Jack Dempsey fish.
They can grow up to 8 inches in length with proper care and a nutritious diet.
A minimum tank of 50 gallons is recommended for Electric Blue Jack Dempsey cichlids.
If you wish to house them in a community aquarium, you will need a larger tank depending on the various fish species.
These fish are less aggressive than some of the other cichlid species.
So they need abundant hiding places in the tank due to their shy nature.
Therefore, the tank should be large enough to accommodate plenty of hiding places so that these fish don’t feel threatened or anxious.
There should also be enough room for them to swim freely.