Cardinals
One of the few groups of shoaling fish commonly available to marine aquarists, Cardinalfish are nocturnal and tend to be quite shy. They require meaty foods and will often not take prepared foods such as flakes and tablets. For the best chance of success, keep a wide variety of frozen foods on hand. In the event of a hunger strike, they will almost always take adult brine shrimp. As far as other care requirements they are similar to damsels: not picky. So long as they are properly acclimated, they tolerate a wide range of parameters. Watch the ammonia/nitrite, as they are particularly sensitive to these chemicals.
The Banggai cardinalfish (Pterapogon kauderni) is a small tropical cardinalfish (family Apogonidae). This attractive fish is popular in the aquarium trade.
This species grows up to 8 centimetres (3 in) total length. It has a distinctive contrasting pattern of black and light bars with white spots. This species is easily differentiated from all other cardinalfish by its tasseled first dorsal fin, elongate anal and second dorsal fin rays, deeply forked caudal fin, and color pattern consisting of three black bars across the head and body and prominent black anterior edges on the anal and second dorsal fin. Males can be differentiated from females by a conspicuous enlarged oral cavity, which is apparent only when they are brooding.
Also known as the bluestreak cardinalfish, it is one of the cardinalfishes.
A translucent fish with vertical irridescent blue lines on the head and front of body. It grows up to 6cm in length. In juveniles the blue lines are missing.
Apogon cyanosoma is a Cardinalfish from the Indo-West Pacific. It occasionally makes its way into the aquarium trade. It grows to a size of 8cm in length.
The Pajama cardinalfish (Sphaeramia nematoptera) is a species of fish belonging to the Apogonidae family. It is a popular aquarium fish. It grows to a total length of about 8.5 millimeters and features distinctive red eyes and a broad dark vertical 'waistband' with scattered red spots toward the tail. It is considered to be of low vulnerability, and is distributed throughout much of the West Pacific, from Java to Fiji, and from the Ryukyu Islands south to the Great Barrier Reef. In Pajama cardinalfish, males incubate the eggs in their mouth until they hatch.
A hardy and peaceful fish that can live many years in a marine aquarium. It will typically not bother other fish, or invertebrates and is therefore considered reef safe. The one possible exception to that rule is they may eat small shrimp.
As they are a social fish, it is common to keep them in groups of five or more. They have been known to breed in captivity, unlike most marine fish, but captive bred specimens are only rarely available. If they are kept with a long spined sea urchin they will hide among the spines when they feel threatened.
A coppery-coloured fish with a broad blackish bar at the base of the tail up to 14.5cm in length. The upper jaw has a narrow blue streak, and a broad blackish stripe extends from the front of the snout to the eye. Easily confused with Apogon fleurieu[2], where the black tail bar does not narrow in the centre, but unlike this species the stripe is also present in juveniles.