Cirrhitichthys oxycephalus – Coral Hawkfish

Cirrhitichthys oxycephalus – Coral Hawkfish

Cirrhitichthys oxycephalus was first described by Dutch ichthyologist Pieter Bleeker in 1855. This fish belongs to the family Cirrhitidae, which is known as the Hawkfish. The family Cirrhitidae consists of 12 genera, including Cirrhitichthys, and contains a total of about 33 species. The common name of this species is Coral Hawkfish.

The genus name Cirrhitichthys is derived from the Latin word “cirrus” meaning “curl” or “fringe” and the Greek word “ichthys” meaning “fish”. The species name oxycephalus is a compound of the Greek words “oxy” meaning “pointed” and “cephalus” meaning “head”, referring to the sharp snout of this fish.

Synonyms: Cirrhites oxycephalus, Cirrhites grandimaculatus, Cirrhites murrayi, Cirrhitichthys corallicola.

Description

General description:
The Coral Hawkfish has an oval, moderately compressed body with a pointed snout and a straight profile. The head and flanks are variably colored from whitish to pink with reddish-brown to grayish or bright red-orange spots. There is a row of smaller spots along the lateral line and large spots on the spiny dorsal fin, including spots along the base of the fin. The soft dorsal fin and the caudal fin are also spotted. This fish species can reach a maximum length of 10 centimeters.

Differences between males and females:
Males are territorial and haremic, meaning they defend a small territory in which they keep a group of females. No specific physical differences between males and females have been described, but behavioral differences are clearly present.

Behavior and Temperament:
The Coral Hawkfish is generally aggressive towards other species and can be very territorial. They live solitarily or in small harems and are often found resting on, in or under hard or soft corals. They are bottom dwellers and use their strong pelvic fins to support themselves while perching.

Swim bladder

Cirrhitichthys oxycephalus has a remarkable feature: the absence of a swim bladder. This feature has several advantages and affects their swimming behavior in unique ways.

Benefits of Lack of a Swim Bladder

1. Stability and Positioning:
The lack of a swim bladder allows this species to sit easily on coral structures without floating. This is particularly useful for their lifestyle, as they often rest on, in, or under hard or soft corals. The strong pelvic fins help them support themselves while sitting, giving them stability in their environment.

2. Energy efficiency:
Without a swim bladder, these fish do not need to expend energy regulating their buoyancy. This can be advantageous in environments where food resources are scarce, as they can focus their energy on hunting and defending their territory rather than maintaining their position in the water column.

3. Avoiding Predation:
The ability to quickly jump from one “perch” to another, similar to the movements of a hawk, helps them to evade predators and surprise prey. This behavior makes them less predictable and harder for predators to catch.

Swimming behavior

1. “Scoot” Movement:
Rather than swimming continuously like many other fish, Coral Hawkfish move by hopping from one perch to another. This behavior is similar to that of a hawk jumping from branch to branch, giving them their common name, Hawkfish. They use their strong pectoral fins to hold onto coral structures and can quickly change position to catch prey or hide from predators

2. Ambush Hunting:
Coral Hawkfish are ambush hunters. They often sit still in a strategic spot and wait for prey to come close enough before striking. This behavior is facilitated by their ability to remain stable without a swim bladder, making them less noticeable to their prey.

3. Limited Movement in the Water Column:
Because they lack a swim bladder, Coral Hawkfish are less likely to swim in the open water column. They tend to stay close to the bottom or coral structures, where they can cling and observe their surroundings for potential prey or threats.

Conclusion Swim Bladder

The lack of a swim bladder in the coral hawkfish provides several advantages that help them survive in their specific habitat. It allows them to be energy efficient, maintain stability on coral structures, and hunt effectively and evade predators. Their unique swimming behavior, characterized by perch-to-perch movements and ambush hunting, makes them well-adapted to life in coral reefs.

Protogynous Hermaphroditism in the Coral Hawkfish

What is Protogynous Hermaphroditism?
Protogynous hermaphroditism is a form of sex change in which an individual begins life as a female and changes to a male later in life. This phenomenon occurs in several species of fish, including the Rodel Coral Climber. It provides an evolutionary advantage because it increases flexibility in reproductive strategies, especially in environments where the sex ratio can vary.

How Does it Work in the Coral Hawkfish?
In the Coral Hawkfish, males are territorial and guard harems of females. When a dominant male dies or disappears, one of the females in the harem can change sex and take over the role of the male. This process is regulated by hormonal changes that stimulate the development of male sexual characteristics.

Behavioral and Physiological Changes:

• Behavioral changes: Females that change sex exhibit changes in behavior, such as adopting territorial behavior and defending a harem.
• Physiological Changes: Sex change involves the development of male reproductive organs and sperm production. Depending on the species and environmental conditions, this process can take several weeks to months.

Benefits of Protogynous Hermaphroditism:

• Reproductive Flexibility: It enables the population to respond quickly to changes in the sex ratio, which is essential for reproductive success.
• Maximization of Reproductive Success: The ability to change sex allows individuals to maximize their reproductive potential over their lifespan.

Ecological and Evolutionary Implications:
Protogynous hermaphroditism in the Red Coral Climber has important ecological and evolutionary implications. It helps maintain stable populations in dynamic environments such as coral reefs, where mate availability can vary. Furthermore, it contributes to genetic diversity within the population, which is crucial for adaptation to changing environmental conditions.

Biotope

The Coral Hawkfish is found in the tropical reefs of the Indian and Pacific Oceans, including the Red Sea, the east coast of Africa, the Marquesas Islands, Micronesia, southern Japan, the Great Barrier Reef and New South Wales. They live in areas with rich coral growth and clear water of lagoons, channels or seaward reefs to depths of at least 40 meters. Their natural habitat consists of coral reefs with an abundance of hard and soft corals, and the bottom consists mainly of coral rubble and sand.

Diet

In the wild:
The Coral Hawkfish feeds primarily on small invertebrates, including crustaceans such as decapods, copepods, and isopods, as well as molluscs such as bivalves and snails. They may also eat small fish.

In the aquarium:
In the aquarium, they can be fed a diet of small crustaceans such as krill, mysis and brine shrimp, as well as larger crustaceans such as shrimp and crabs. It is important not to feed them coral polyps or small fish as they may eat these, meaning they are not completely reef-safe.

The Aquarium

Aquarium Size:
The minimum volume for keeping a Coral Hawkfish is 100 liters (26 gallons). For multiple pairs, a larger aquarium is needed to minimize territorial conflicts.

Decoration:
The aquarium should be decorated with lots of coral and rocks to provide sufficient hiding places and places to sit. A substrate of sand or fine gravel is suitable.

Water Parameters:
The best water parameters for this species are a temperature between 23.2 and 25.9 °C, a pH of 8.1-8.4, and a salinity of 1.020-1.025.

Introduction:
This species is best introduced into a well-matured aquarium with sufficient algae and microfauna.

Compatibility:
The Coral Hawkfish does well with other non-aggressive reef fish such as clownfish, surgeonfish and gobies, but should not be kept with small fish or invertebrates that could be seen as prey.

Breeding aquarium and conditioning

There are no specific data on breeding the Coral Hawkfish in an aquarium.

Particularities

A special feature of the Coral Hawkfish is that they do not have a swim bladder, which helps them to sit easily on coral structures without floating. They are also known for their territorial behavior and can be aggressive towards other fish that invade their territory.

Conclusion

The Coral Hawkfish is an interesting and colorful addition to a well-established reef tank. However, they are not suitable for beginners due to their aggressive behavior and specific dietary requirements. It is important to provide plenty of hiding places and perches and to keep them with compatible species to minimize stress and aggression.

Video

Author

John de Lange

Copyright images

Doug Anderson
Rickard Zerpe – CC BY 2.0
Francois Libert (Zsispeo) – CC BY-NC-SA 2.0
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