Blue Spotted Jawfish

The Blue Spotted Jawfish, scientifically known as Opistognathus rosenblatti, is a visually striking fish with captivating features. It has a maximum size of around 3 inches (7.6 centimetres), making it relatively small in the marine world. The most notable characteristic of this species is its rich orange colouration, adorned with distinctive blue spots across its body.

Taxonomy

The Blue Spotted Jawfish belongs to the genus Opistognathus and is a member of the family Opistognathidae. Within its genus, it shares identifying features such as a protruding lower jaw and a slender body. The closest relatives of the Blue Spotted Jawfish include other jawfish species found in similar marine environments. The scientific name Opistognathus rosenblatti is derived from a combination of Latin and the name of renowned marine biologist Richard H. Rosenblatt.

Natural Habitat

In its natural habitat, the Blue Spotted Jawfish inhabits shallow coastal areas and coral reefs. Its surroundings are filled with a vibrant array of coral formations, ranging from delicate branching corals to massive boulder corals. These areas provide ample hiding spots and shelter for the jawfish, as it prefers to construct and reside within its burrow.

Keeping Blue Spotted Jawfish Healthy:

The care level for Blue Spotted Jawfish is considered moderate, requiring some attention to ensure their well-being. They thrive in a marine aquarium with stable water parameters, including a temperature range of 75-80°F (24-27°C) and a pH level between 8.1 and 8.4. Maintaining appropriate salinity levels around 1.025 specific gravity is crucial for their health. Regular water changes and adequate filtration are essential to maintain water quality.

Special Requirements and Feeding

Blue Spotted Jawfish have specific requirements to promote their overall health and vitality. They prefer a sandy substrate in the aquarium to enable their natural burrowing behaviour. Providing suitable hiding places, such as a coconut shell or blenny home, allows the jawfish to feel secure and reduce stress.

Feeding the Blue Spotted Jawfish is relatively straightforward, as they readily accept a diet consisting of small meaty foods. Offer a variety of live or frozen foods, including brine shrimp, mysis shrimp, and small pieces of fish or shrimp. Providing a balanced diet rich in nutrients helps to ensure their optimal growth and vibrant colouration.

How Many Should I Keep?

When considering the number of Blue Spotted Jawfish to keep, it is essential to provide each fish with sufficient space and territory. Due to their territorial nature, it is advisable to house only one jawfish per tank, unless in a large and well-established aquarium with ample hiding spots.

Behaviour

Blue Spotted Jawfish are full of charisma and fascinating to observe as they interact with their environment. They spend a significant amount of time near their burrow, often popping in and out to survey their surroundings like a grumpy old man fussing about his lawn. Providing a suitable burrowing substrate and additional hiding places mimics their natural behaviour and creates a comfortable habitat.

Lighting Preference

Blue Spotted Jawfish thrive under moderate to high lighting conditions. This enables them to showcase their vibrant blue colouration and enhances the overall aesthetics of the aquarium. Providing a combination of natural daylight and appropriate aquarium lighting fixtures supports their well-being.

Suitable Tank Mates

When selecting tank mates for Blue Spotted Jawfish, compatibility is crucial. Avoid aggressive or larger fish that may intimidate or harm the jawfish. Suitable companions can include peaceful reef fish, and other non-aggressive species that inhabit different levels of the aquarium.

Reproduction in the Wild

Blue Spotted Jawfish, scientifically known as Opistognathus rosenblatti, exhibit interesting reproductive behaviours in the wild. They are known to be monogamous, forming pair bonds during the breeding season. This species follows an egg-guarding reproductive strategy, where the male assumes the primary responsibility of caring for the eggs.

Breeding Opistognathus rosenblatti:

1. Set Up:

To successfully breed Blue Spotted Jawfish in captivity, a well-maintained marine aquarium with appropriate conditions is necessary. The tank should have a sandy substrate and ample hiding spots, such as small caves or PVC pipes, to mimic the jawfish’s natural burrowing behaviour. The water temperature should be maintained between 75-80°F (24-27°C), and the pH level should range from 8.1 to 8.4.

1. Courtship/Spawning:

Courtship behaviour in Blue Spotted Jawfish involves a series of intricate movements and displays. The male jawfish initiates the courtship by performing a “headstand” display, where it positions its body vertically and vibrates. This behaviour signals its readiness to breed. The female responds by performing a circular dance around the male, showing her acceptance.

Once courtship is successful, spawning occurs. The female releases a cloud of eggs while the male simultaneously releases sperm to fertilize them. The male quickly collects the fertilized eggs in his mouth and carries them inside his buccal cavity for incubation and protection.

1. Rearing:

The male diligently guards the eggs, not eating during this period, which typically lasts around 7-10 days. He periodically opens his mouth to aerate the eggs and remove any debris. Once the eggs hatch, tiny larvae emerge, resembling miniature transparent versions of the adults. At this point, the larvae become pelagic, drifting in the water column before eventually settling to the substrate.

Sexual Dimorphism

Blue Spotted Jawfish do not exhibit significant sexual dimorphism, meaning the physical differences between males and females are minimal. Both genders possess similar vibrant blue spots on their bodies. The main distinction lies in their reproductive roles, with the male being responsible for incubating and protecting the eggs.

Distribution

The Blue Spotted Jawfish, Opistognathus rosenblatti, is native to the Eastern Pacific Ocean. Its natural range includes the waters off the coast of Mexico, specifically in the Gulf of California. While there may be captive bred and line bred strains available, the original fish originate from this region.

Summary

The Blue Spotted Jawfish, Opistognathus rosenblatti, is a captivating marine species known for its vibrant blue pattern and unique reproductive behaviours. In the wild, they form monogamous pair bonds and practice egg-guarding, with the male taking on the responsibility of caring for the eggs. Breeding Blue Spotted Jawfish in captivity requires a well-maintained marine aquarium with appropriate conditions. During courtship, the male performs a distinctive headstand display, and spawning occurs when the female releases a cloud of eggs. The male collects and incubates the fertilized eggs in his mouth until they hatch. The Blue Spotted Jawfish is native to the Eastern Pacific, particularly the waters off the coast of Mexico. While captive bred and line bred strains may be available, the original fish originate from this region.