**Ostorhinchus angustatus**

Ostorhinchus angustatus – Broadstriped Cardinalfish for Reef Aquariums

Ostorhinchus angustatus, also known as the Broadstriped Cardinalfish, is a peaceful marine fish belonging to the Apogonidae family. Its pale body, white-silver to slightly pinkish, is marked by five horizontal dark brown to coppery stripes. A distinctive black spot at the base of the caudal fin completes its coloration.

This species can reach about 11 cm as an adult. Native to the tropical Indo-Pacific, it has a particularly wide distribution range, from the Red Sea and the coasts of East Africa to the Pacific islands, Japan, and New Caledonia.

A discreet and mainly nocturnal cardinalfish

Ostorhinchus angustatus naturally inhabits outer reefs, reef slopes, and rocky areas with many cavities. It is found at depths of around 6 to 65 meters.

Like many cardinalfish, it is relatively discreet during the day. It then seeks shaded areas, caves, and overhangs in the aquascape. At dusk, it becomes more active and leaves its shelter more often to search for food.

Care conditions for Ostorhinchus angustatus

• Recommended minimum tank volume: about 120 liters
• Adult size: up to about 11 cm
• Temperature: 24 to 27 °C
• pH: 8.1 to 8.4
• Specific gravity: about 1.020 to 1.025
• Decor: rocks, caves, and many shaded refuges
• Water movement: moderate

The aquarium should provide enough sheltered areas so the fish can retreat during periods of strong lighting. A layout made up of rocks forming caves, crevices, and overhangs is particularly well suited to its natural behavior.

Behavior and compatibility in the aquarium

Ostorhinchus angustatus is generally peaceful toward other fish. In the wild, it may be seen alone or in small groups. In the aquarium, it can therefore be kept individually or with several conspecifics when the tank size and number of refuges are sufficient.

It is best paired with fish that have a calm temperament. Very aggressive or particularly active species may keep it hidden all the time and limit its access to food.

This species is suitable for reef aquariums and does not pose any particular danger to corals. Some caution is still recommended with very small crustaceans and tiny shrimp, which may potentially be regarded as prey.

Feeding Ostorhinchus angustatus

Ostorhinchus angustatus is primarily carnivorous. In its natural environment, it feeds at night on small benthic invertebrates, especially polychaete worms and small crustaceans.

In the aquarium, a varied diet can be offered:

• Frozen mysis
• Live or frozen brine shrimp
• Finely chopped krill
• Small crustaceans and zooplankton
• Appropriately sized carnivorous pellets

Recently introduced individuals may be relatively shy at feeding time. It is then advisable to offer food near their refuges and possibly at the end of the day, when their activity increases.

A reproductive strategy typical of cardinalfish

Ostorhinchus angustatus is a mouthbrooding species. After spawning, the male keeps the fertilized eggs in his mouth to protect them during development until hatching.

This characteristic reproductive behavior of cardinalfish can sometimes be observed in the aquarium when several compatible individuals are kept together under good conditions.

Why choose Ostorhinchus angustatus?

• Elegant coloration with five dark horizontal bands
• Distinctive black spot at the base of the caudal fin
• Peaceful and discreet behavior
• Compatible with reef aquariums
• Can live alone or in a small group
• Interesting nocturnal behavior to observe

Ostorhinchus angustatus is an excellent choice for aquarists looking for a peaceful and original cardinalfish. Its longitudinal stripes, mainly crepuscular and nocturnal behavior, and its tendency to move around caves and overhangs give it a presence unlike fish that constantly swim in open water.

In a stable reef aquarium with many hiding places and calm tankmates, it can quickly find its place and display its natural behavior.