|
Aptly named for its brilliant red to light pink colors, the Cardinal fish can be easily found among the coral reefs in shallow water areas. In most cases this family of fish will have large ctenoid scales on their bodies but occasionally some species are found with cycloid scales. This fish has a large head and eyes, with an angled mouth that causes the lower part to protrude slightly. In most cases the teeth are small lining the jaws and gums, but some cardinal fish like those in the Cheilodipterus genus have longer grasping teeth. They have two dorsal fins that appear to be rather long for the size of their body as well as an anal fin with only two spiny rays. Close inspection of a cardinal fish will show that the lower jaw is separated and contain small, sharp teeth. The majority of this family can be found inhabiting the waters of the Indo-Pacific but some species prefer brackish water areas while others only inhabit fresh water. One such species can be found in New Guinea throughout the Lorentz River. This silvery, light yellow species, Apogon trifasciatus, is around five inches in length and has fins covered with cycloid scales.
One of the more interesting facts about the cardinal fish is their common characteristic of mouth brooding. Once the eggs are released and fertilized the female, or in some species the male, will take the eggs in their mouth where they will incubate until they have hatched and are ready to feed. In some species of the cardinal fish, such as the red-orange cardinal fish that is often found in the Mediterranean, both the male and female become active in this process. Some cardinal fish, such as the Banggai cardinal fish, have been successfully kept in salt water aquariums. Studies of this beautiful fish show that part of the mating ritual includes a kind of circling and nipping prior to the fertilization of the eggs. Once the male of this species has received the fertilized eggs into his mouth he will not eat until they have hatched. During this time the female will aggressively chase away any other fish that come too close to the male. Even after hatching the fry remains in the males mouth for a few days before the spits them out in groups to search for food. Studies have noted that this process can take up to 24 days with the male refusing to eat for around two weeks of this time.
The cardinal fish is, in most cases, a nocturnal fish ranging in size from between two and eight inches in length. While many of these fish bear the cardinal colors in a wide range of reds such as the Apogon multitaeniatus which is the largest species reaching an average length of around seven inches, there are some species whose colors range from greenish, yellow-brown, silver, black to pink. There are around 200 species of this fish with most living in shallow reef areas. One species, the Astrapogon stellatus, that is found in the Caribbean has been known when threatened by a predator to take cover inside conch shells that are still inhabited by their owners. In the Tonkin Gulf one of the more interesting cardinal fish was found that had luminous organs. The Apogon ellioti was discovered to have glandular organs within the digestive tract that are structured similar to a reflector and lens. It is still unknown what purpose these organs play in the life of this species but it is known that there are other luminous species that inhabit some of the deeper coral reef areas of the Indo-Pacific.
|
| |
