[Phylum: Chordata] [Class: Actinopterygii] [Order: Kurtiformes] [Family: Apogonidae (ray-finned)]
There are several hundred different species of cardinalfishes (Genera Apogonidae). Most have a lateral (sideways) compressed body and large, bulging eyes.
This section contains fun facts and interesting information about the cardinal fish genus, where to find them, what they eat, and how they reproduce.
Most cardinalfishes are marine life animals which thrive best in tropical and subtropical waters.
In general, you find them seeking shelter around rocky reefs in shady, shallow environments, such as:
Common areas to find ray-finned cardinalfishes are the Atlantic Ocean, the Indian Ocean, and some regions of the Pacific.
Other distributions of some species, such as the Mediterranean cardinal fish (Apogon Imberbis), congregate in the warmer regions of the eastern Atlantic (e.g. the Gulf of Guinea).
It's not uncommon to find some species in brackish water, and a few others in fresh water, such as the Glossamia aprion (Queensland mouthbrooder).
The ovate (egg-shaped) body of most cardinal fish species is easy to identify. In addition, their large head stands out against the short, upturned snout.
A protruding lower jaw, shorter than sling-jaw wrasses, contains rows of tiny villiform teeth. The long pectoral fin stretches down to the start of the anal fin. You should also see signs of emargination in the caudal fin.
Here's the thing:
These ray-finned fishes have large ctenoid scales. It is also common for most cardinalfishes to have two or three dark spots running along the base of the caudal fin.
Almost all Apogonidae are small, especially Kurtiformes. They rarely grow bigger than ten (10) centimetres long.
Nonetheless, the maximum recorded size for the 'King of the Mullets cardinal fish' is fifteen (15) centimetres (6 inches).
Having big eyes means this species is content with spending a lot of the daytime hours in dark ravines. It becomes a lot more active in deep water at night to hunt for food.
When the water temperature warms, they tend to stay in a depth range of ten (10) to seventy (70) metres.
But, they will dive deeper to escape the coldness during the winter months - down to two hundred (200) metres.
The cardinal fish is a carnivorous predator that feeds on:
Many of the Mediterranean dive sites offer ideal opportunities to catch sightings of this species as they search for food scraps, especially around artificial reef structures.
In fact, oviparous reproduction in fishes is commonplace, and parental care is mostly praiseworthy for cardinal fish families. Even so, the males have been known to eat the eggs, often by accident during the courtship ritual.
Internal fertilisation takes place through 'palpitating' movements. This tends to be a weak nuptial dance performed between the fins of the mating partners.
Typically, at least three (3) females will accompany one male in advance of the spawning event. The outcome can turn out to be batches of up to 20,000 eggs.
Male cardinalfish keep the eggs inside its mouth until they hatch. So, until the male expels the eggs, around eight (8) days later, it does not eat any food.
In fact, the threat status for the Mediterranean cardinalfish species in Europe is of 'Least Concern' according to the information on the IUCN website.
But, even though they are not endangered, fishers sometimes use them for bait. Plus, they are also consumed by humans and traded by aquarists for the pet aquarium industry.
The symbiotic relationship between A. stellatus and a species of large sea snails (the queen conch) is under threat, mostly due to over-fishing.
This guide contains interesting facts about Astrapogon stellatus conchfish and why alternative refuges with Atrina rigida (the rigid pen shell) could be key for their survival.
This small, bony fish is actually endemic to the Banggai Archipelago, found between the Sula and Celebes islands in Indonesia.
It's quite easy to identify the ovate (egg-shaped) cardinal red body of Apogon imberbis. The large head is noticeably larger than the short, upturned snout.
This guide contains facts and information about the Mediterranean cardinalfish (also called the King of the Mullets) and how they differ from other ray-finned fishes.
Note: The short video contains footage of the Apogon imberbis (Cardinal fish) swimming and feeding in a natural dusky habitat.