Saltwater aquarium fish

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Pajama Cardinals

Pajama Cardinals have been very popular in salt water tanks for quite a few years now, they are proving to be as popular as their close cousins the Banggai Cardinals, a lot of this has to be due to their unique colouration and markings, their peaceful nature towards other tank mates and the ability to spawn in many keepers aquariums, a real bonus with marine fish.

They can be found under many common names such as the Polka-Dot Cardinal, the Spotted Cardinal, the Coral Cardinal and the Red Spotted Cardinal but they are all the same fish. Their Latin name is Sphaeramia nematoptera and they belong to the family of Apogonidae. They get their common names form the strange markings that comprise of red, yellow or silver with a greenish face. The back half of their body is normally silver with red dots and this is separated by a dark band that runs down their body from the dorsal fin. As these fish are nocturnal they have larger eyes than some other species of fish and this makes them all the more appealing.

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They are an excellent selection for any keeper new to salt water fish keeping as they are very hardy, they can be kept in small groups and they also travel well. Often fish that are poor travellers arrive with some disease or other but not with these, they settle into the tank quickly and are very low maintenance. As they are so easy to breed the number of tank bred specimens available is very high, this keeps the price of the fish down and also means that tank bred specimens are also capable of adapting to a wider range of water parameters.

In the wild they are found all around the Western pacific namely in North-eastern Australia, Papua New Guinea, and the Philippines where they tend to stay close to the reefs and will have territories that they stick to and use as bolt holes when escaping from predators. They also have an unusual habit of using sea urchins for protection and will hide in the spines until it is safe to emerge, replicating this in the aquarium is beneficial for these fish.

Caring for Pajama Cardinals

When setting up your aquarium for these fish make sure that there is plenty of rock work, these do particularly well in a reef aquarium, if no urchins are added to the tank, try to create a dummy urchin as these fish will use it when they feel threatened. The temperature should range between 22 22-26 deg C (72 -78 deg F) and the salinity should range from 1.021-1.025. The water quality should be kept high and regular water changes will need to be performed to aid in this. It is best to keep a small group of fish but try to avoid keeping a group of males together, it is far better to keep one male with several females, they will be peaceful with other tank mates but there may be some bickering between each other especially when first added to the tank until they form their own pecking order. They may hide away a lot initially during the day but may become bolder as they settle and venture out hen the lights are on, night-time is when they become most active and they are often nicknamed ‘the damsel of the night’.

Feeding Pajama Cardinals

When you first add your Pajama Cardinals to the aquarium they may hide away for long periods and refuse to take the food that you offer them, this phase should quickly pass and they will begin to eat on a regular basis. Tank bred specimens will settle in quicker and will probably accept commercial foods as well as a variety of live or frozen foods. Wild caught specimens may decide to only accept live or frozen foods, swimming away from marine flake etc. Chopped prawns and chopped cockles and mussels should also be accepted by this fish.

As these are nocturnal fish it is best to add the food for these fish as soon as the lights go out, this is when they are at their most active and in the wild they would naturally begin to search for food at this time.

Breeding Pajama Cardinals

As with all salt water fish, breeding these can be a bit of a hit and miss project. It is very difficult to sex these fish, the general guidelines are that the males are larger then the females and as they are mouth brooders, the males will have larger mouths for this purpose. The easiest way to obtain a pair is to purchase a small group and let them pair off naturally. Two males in the tank will fight so if this occurs remove any that are being bullied so that the dominant male remains. Condition the fish with plenty of live or frozen foods and after a few months a pair should form and spawning will commence. Often the spawning will happen through the night and will not be noticed by the keeper, the sure sign that it has occurred is by observing the male, his mouth will be larger than normal and he will probably refuse food will carrying eggs.

The female will take no further part in the parental duties and may be chased away by the male but this is normal and nothing to worry about. After 21 days the male will release fry, this can take 2-3 days for all of the fry to be released and the total brood will vary between 20-30 young. They are quite a decent size when released and easy to spot so they should be netted into another rearing tank for their own safety.

The fry can be fed exclusively on newly hatched brine shrimp, feed them small meals 3-4 times per day to allow them to digest the food each time and they will show visible signs of growth after 4 weeks. At this stage they should accept other live or frozen foods that are offered.
Document modified on Sat Dec 8 22:03:57 UTC 2018
Document created on Sat Jun 12 6:15:00 UTC 2010
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