Pajama Cardinalfish Care Guide and Tank Setup – 2021


The Pajama Cardinalfish when it comes to tank visuals. They almost look photoshopped because of their large eyes, distinct polka dots covering their body’s mid-section, and two prominent transparent fins.

These features make them an obvious favourite among hobbyists plus their care sheet isn’t very demanding either.

Beginners should have no difficulty in creating ideal tank conditions to keep them happy. Pajama Cardinals are very peaceful and prefer to swim with a school of similar species, splitting off at night to hunt for food.

Here is the complete care sheet for Pajama Cardinalfish and a few bonus points.



Category Rating
Level of Care Easy
Temperament Very timid
Appearance Silver posterior with polka-dotted midsection and transparent dorsal fins
Life Expectancy Can live for 4 years
Size Reach a size of 3 ½” to 4”
Diet Carnivorous
Family Apogonidae
Tank Size 20 gallons per fish, larger for a school of fishes
Tank Environment Plenty of live rock with coral structures
Tank Mates Very peaceful with other community fish


Pajama Cardinalfish Overview


The Pajama Cardinalfish is a member of the Apogonidae family. Other common names include Polka-dot Cardinalfish, Spotted Cardinalfish, and the Pajama Cardinalfish.


They originate from the Indo-Pacific oceans and swims near coral structures. These marine water species found near Papa New Guinea, the Philippines, and Northern Australia.


Being a hardy fish species, they are among the best choices for beginners who want to start a saltwater tank. They are forgiving and tolerate most water conditions, and may even breed in the aquarium without much input. Because they’re so widely available, the Pajama Cardinalfish is relatively less expensive and found in most online stores.


pajama cardinalfish


Pajama Cardinalfish Appearance



The Pajama Cardinalfish has a unique body with distinct sections. From the get-go, you’ll see massive tubular eyes with big lenses that give them binocular vision and great sensitivity to small changes in visual intensity.


The rest of their head is either bright silver or a yellow hue, with a dark stripe that continues to the dorsal fin’s edge. This black band allows them to blend in with sea urchins, allowing them to camouflage against their long spines.


Both dorsal fins are broad and extremely transparent, which makes for an enjoyable visual experience for owners. Their posterior has a silver backdrop covered with distinct orange polka dots.


All these visual features make them a standout feature of the Pajama Cardinalfish is their rigid body seems to float, rather than swim, with a wiggle than any other marine fish.


Pajama Cardinalfish Characteristics – Detailed Guide on Behavior


The Pajama Cardinalfish is a peaceful and timid fish, so much so, that they wouldn’t fight for food when other fish seem to be competing with them for it.


They are schooling fish, so it’s good to keep at least two of them in the same tank, if not more. If other fish are giving it a hard time, try adding another Pajama cardinalfish to tank for encouragement.


In terms of interacting with the tank, they behave much like Neon Tetra, floating or darting around the tank. When you first introduce to the tank, they’ll see them hiding behind structures and caves.


They’ll quickly get adjusted to the new environment and won’t stay hidden long. Pajama less-than-conspicuous body means that they cannot cover themselves behind rockwork.


They prefer to set up their home in an open area. They like to spend most of their time floating near one spot, doing short laps around the tank before returning home.


Their favourite hobby is to hang under rocks and corals, which could be taken by other tank mates if the Cardinalfish not introduced before everyone declares their territory.


They do run into trouble with tank mates, especially those belonging to the same family. For the most part, they are very peaceful. Because they can’t defend themselves, you should make sure that no other fish is harassing the Cardinalfish too often. The elevated stress levels could compromise their immune systems and make them susceptible to diseases.


When you first introduce them into the aquarium, expect the Cardinalfish to be subject to frequent harassment by other fish. Shouldn’t last long, however, and any aggression should subside after a few days. If the hostility continues even after several days, you can restore order by trying the following strategies


  • Reset all the aquaspacing in the tank
  • Add more rockwork to provide the Cardinalfish with additional hiding spaces
  • Add more Pajama Cardinalfish to create a safe space for them


n most cases, you won’t have to take things to such an extreme.

Although Pajama Cardinalfish aren’t known for jumping out of their tank, you should consider securing the tank top with a tight lid to prevent them from escaping. After all, they are only 3″ in length.


When the Pajama Cardinals start pairing off to mate, their aggression levels will spike, and you’ll see much in-fighting. Do keep an eye out for excessive violent behaviour during the mating season.


pajama cardinalfish tank mates



Pajama Cardinalfish Compatibility: Tank Mates



When keeping Pyjama Cardinalfish, the rule of thumb is not to place them in the same tank as aggressive fish species because they bullied to the point of death.


Because they’re so timid, it’s always good to keep them in pairs with their kind. They’ll swim in groups, warn each other of predators, and alert each other when it’s feeding time.


Potential tank mates for the Pajama Cardinalfish are non-aggressive and similarly sized fish species. A list of ideal tank companions is as follows


  • Filefish
  • Clownfish
  • Gobies
  • Wrasses
  • Dwarf Angelfish
  • Dragonets


While the Pajama Cardinalfish’s care requirements are at the end of the spectrum, the hardest part is to get them to acclimate to their surroundings (and tank mates).


You’ll find yourself frequently breaking up fights and on-going harassment. If bullying persists, you should consider removing the aggressor in a separate tank or risk having your pet Cardinalfish die.


Avoid large, aggressive species such as hostile wrasses, hawkfish, and Dottyback that could threaten peace in the tank. It is worth noting that Pajama Cardinals will go after smaller fish such as nano-gobies.


Pajama Cardinalfish Diet


The Pajama Cardinalfish is exclusively carnivorous and enjoys a meaty diet comprising of frozen and live foods. They will also accept prepared foods such as pellets and flakes.


Their favourite frozen foods include brine shrimp, bloodworms, and Mysis shrimp. Their options for live food are significantly less, however, because of their relatively small size.


They will gladly hunt live baby brine and feeder shrimps just as quickly. They are nocturnal hunters and will hunt for small crustaceans at night. It is preferable to feed them at night or during twilight.


It is essential to keep their diet varied to ensure the fish remains healthy. The excellent idea is to feed them live brine shrimp. You can provide the shrimp with a range of nutritious foods and pass them on to the Pajama Cardinalfish.


It may be a little difficult for beginners to recreate because you’ll need a shrimp’ farm’. It’s an option worth considering if you’re deep into the fishkeeping hobby.


Your Pajama Cardinalfish shouldn’t have a problem eating because they’re quick and may get alerted by their school members who detect food. For this reason, it’s always a good idea to pair them with another Pajama Cardinalfish – they help one another get adjusted to the local environment.


If the fish run into an aggressive species, they’ll give up and let them claim their share of the food. If this happens too often, you may have to become creative and try feeding your Cardinalfish on both sides of the aquarium. One side will distract the aggressor while the other side helps the Cardinalfish eat in peace.


Feed the Pajama Cardinalfish at least 5 to 6 times per week. Feed them only as much as they can eat within 2 to 3 minutes; otherwise, the food could upset the tank’s nitrate and nitrite levels.


pajama cardinalfish tank conditions



Pajama Cardinalfish Tank Conditions



While you should always aim for a bigger tank, you can make do with a 30-gallon aquarium for a single Pajama Cardinalfish. Below is a list of the water conditions that you should strive to achieve:


  • Temperature: 76-80° F
  • Specific Gravity: 1.025
  • pH value: 8.2-8.4
  • Calcium levels: 420-440 ppm
  • Alkalinity: 8-9.5 dKH
  • Magnesium levels: 1260-1350 ppm
  • Nitrates less than10ppm
  • Phosphates less than 0.10ppm


Keep the water chemistry within the following ranges to keep your Pajama Cardinalfish happy:

  • Ammonia at 0 ppm
  • Nitrites at 0 ppm
  • Nitrates under ten ppm (change the water frequently if the nitrates rise above ten ppm)
  • Calcium level at 420 to 440 ppm
  • Magnesium levels at 1270 to 1340 ppm


Install a thermometer to monitor the temperature of the tank. Please do not allow the temperature to fluctuate too frequently and keep it within 2 degrees for the best results. If you live in colder or warmer regions, consider installing a heater to achieve the listed temperature.


Things to Add in the Tank for the Pajama Cardinalfish


Pajama Cardinals are bottom-dwellers and prefer to swim near corals, rock works, and sponges. Make sure to install a lot of caves for them to hide in should they feel threatened.


They are not known for nipping at live corals and should do fine in a reef tank. We can find Pajama Cardinalfish hovering under rocky overhangs in the shade, or near caves and corals during the daytime.


Install a high-quality filtration system that can create a brisk water movement. If you want to install lights in the tank, choose low-intensity options. You can also use light fixtures to encourage your Pajama Cardinalfish to become diurnal. You can do this by offering them food during day time.


These fish also prefer to live near live plants, particularly seaweed. Here is a list of plants that your Pajama Cardinal will love:

  • Green Finger Algae
  • Red Gracilaria Algae
  • Turtle Grass Shoots
  • Mermaid’s Fan
  • Shaving Bush Plant


Breeding Pajama Cardinalfish


Pajama Cardinalfish breeding is simple enough for beginners. The first step is to create a pair. Can achieve it by purchasing 4 or 5 Pajama Cardinals as juveniles and letting them form teams until they reach adulthood.


It can be a bit tough to identify males from females. But the males will have a slightly bigger secondary dorsal fin than females. Females will have slightly rounder bodies than males.


You’ll have to be very patient to get them to start pairing, though. Fish take several months of feeding to get ready for spawning.


Once the pair starts to mate, the courting process will take several days. Pajama Cardinals are mouthbrooders, which means that the male will incubate the eggs in his mouth until they hatch. Males will not eat the eggs during this time, and the female will protect the male until all the fry has emerged.


Caring for Pajama Cardinalfish Fry


Pajama Cardinalfish fry is hardy from the get-go and will start swimming right away. But at this point, males will view their fry as food and must be separated. Use a turkey baster to feed the fry with brine shrimp until they’re old enough to eat independently. The fry grows relatively quickly and is not very sensitive compared to other marine fish. It


pajama cardinalfish diseases



Pajama Cardinal Fish Care: Dangers and Diseases



Pajama Cardinals are usually very hardy and have well-developed immune systems that allow them to ward off parasites and infections. However, they’ll become susceptible to diseases if you will enable the tank’s conditions to deteriorate. If you notice diseases in the tank or ich, use garlic treatment to boost the Cardinalfish’s immunity and expel parasites.


You can make do with a simple 5-gallon aquarium (cover the sides with black cardboard), sponge filter, heater, and a siphon system to change the water with the main tank.


The main tank acts as a filter system to keep the fry’s aquarium at healthy levels. The main tank should slow drip through 5 to 7 days, increasing the flow rate as the fry grows bigger.


During this time, the Cardinalfish fry is highly sensitive to high levels of ammonia. Use an ammonia badge to keep you informed of the tank’s ammonia levels.


Start a rotifer culture at least 3 to 4 weeks before collecting eggs. Rotifers provide the ideal starter diet for your newly hatched fry. 

Another essential food item is microalgae, such as Nannochloropsis paste. It could significantly increase the survival rate of the fry.


How Long do Pajama Cardinalfish Live?


The average pajama cardinal fish lifespan is almost four years. They are relatively hardy and can survive a range of tank conditions, and in some cases, they may live past six years or more.


Can My Pajama Cardinalfish Eat Fish Flakes?


They are carnivorous species but will accept most foods, including fish flakes. Just make sure to provide them with a varied diet. One of too much food is not ideal.


How Many Pajama Cardinalfish to Place in a Tank?


Although Pajama Cardinals can live independently, We can keep them in the tank as a school of 4 to 6 fish. It allows them to form breeding pairs and quickly adjust to their new environment. They also become less susceptible to aggressive bullies.


Where to Buy Pajama Cardinalfish


You can buy Pajama Cardinals for sale from most marine pet stores, online stores, and online forums. They can be purchase for as low as $17 to $40, depending on availability and your location.


Before buying the Pajama Cardinalfish, you should inspect them for diseases and parasites. Only pick healthy specimens that have clear, large eyes, with intact and undamaged fins.


They should also display a vigorous appetite for food, which is a sign that they’re healthy. Before introducing Pajama into your tank, make sure to quarantine the Pajama Cardinals to ward off any parasites and diseases.


A quarantine period of two weeks should help you determine if your Pajama Cardinal is ideal for the tank.


saltfish in water


Are Pajama Cardinalfish Worth Adding to Your Saltwater Tank?



Pajama Cardinalfish may well be the most stunning feature of your saltwater tank. They’re passive (perhaps a little too passive) and will get along well with just about everyone – except nano-gobies.


They are reef-friendly and won’t harm ornamental invertebrates. Their preferred habitat is relatively easy to recreate by most beginners at home.


Breeding also comes easy, make sure to introduce 4 to 6 of Cardinals as juveniles to encourage mating. All in all, when compared to other saltwater fish, they are ideal choices for beginners.


Click Here to Checkout 27 Most Popular Saltwater Fish for your Aquarium


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