Bryaninops natans – Purple-eye Goby

Bryaninops natans – Purple-eye Goby

Bryaninops natans was first described by Larson in 1985. The Purple-eye Goby belongs to the family Gobiidae (Gobies).

The genus name Bryaninops refers to a fish related in appearance to the genus Bryanina, which in turn is synonymous with Sicyopterus. The suffix “-ops” indicates appearance or appearance. The species name natans, from the Latin word for “swimming” or “floating,” describes the fish’s distinctive behavior of hovering above coral, as opposed to the more cryptic, clinging behavior of other related species.

Bryaninops natans is commonly called Purple-eye Goby. An obvious reference to the purple color of the eye and the spot above it.

Description, Behavior and Life Expectancy of Bryaninops natans

The Purple-eye Goby(Bryaninops natans) is a small fish, growing up to 2.5 centimeters in length. The body is elongated and slightly flattened. The head and flanks are translucent except for the abdomen which is yellow. The top of the body often shows faint pink and black saddle-shaped bands. The eyes are a striking pink to red color, which explains the name “Purple-Eye Goby.” The fins are translucent pink.

Bryaninops natans is a shy fish that lives in groups, ideally in groups of at least six specimens. In the wild, they hover above Acropora coral, a few inches above the coral branches. They are not aggressive and are considered peaceful toward other small fish species, provided they are not too small to serve as food. They live in the mid-water column.

Biotope and Ecology of Bryaninops natans

Bryaninops natans occurs in the Red Sea down toward Madagascar in the Indian Ocean. From Japan down to the Great Barrier Reef and further west in the Pacific Ocean as far as Guam and Micronesia. They live there among Acropora corals at depths of about 7 to 27 meters. You can find them in groups between or above certain Acropora corals.

Diet

Diet in the wild: Bryaninops natans in the wild eats plankton, which they pick up while hovering above Acropora coral. They have been observed filtering small food particles from the water column.

Diet in the aquarium: Given their diet in the wild, it is advisable to feed Bryaninops natans in the aquarium with fine, suspended foods such as phytoplankton and nauplii (Artemia salina). Very fine freeze-dried foods may also be suitable. It is important to feed small amounts several times a day to ensure they get enough nutrients.

The Aquarium

For a group of six Bryaninops natans, an aquarium of about 50 liters is sufficient. Larger groups require a larger aquarium , keeping in mind at least 10 liters per fish. The decoration should mimic the natural habitat. It is recommended to use live rock to create hiding places and simulate a more natural environment. A fine sand substrate is suitable. It is important to create sufficient current, but avoid too strong currents that could stress the fish. Adding live coral, such as Acropora, is possible, but requires extra attention to water parameters and compatibility with the fish.

Water values: The ideal water values for Bryaninops natans are a temperature between 25 and 29 degrees Celsius, a pH of 8.1-8.4 and a specific weight of 1.025. The exact values may vary slightly depending on the specific conditions.

Introduction to the aquarium: It is recommended to let the aquarium mature properly before introducing the fish. This allows the biological balance to stabilize and the water quality to be optimal. The presence of algae is not essential for fish survival, but a stable ecosystem is important.

Compatibility with other inhabitants: Bryaninops natans can be kept well with other small, peace-loving fish species that are not too small to serve as food . Suitable tank mates may include small cardinalfish, dwarf emperor fish, and other small, peace-loving gobies. It is important to avoid keeping together species that are aggressive or that might consider Bryaninops natans as food. Larger fish or aggressive species should be avoided.

Details of Bryaninops natans

The documents reveal some interesting details about Bryaninops natans not previously covered in this article:

• Floating behavior: Unlike other species within the genus Bryaninops, which cling to their habitat, B. natans is able to float, a few inches above Acropora coral. This unique behavior is also the reason for the Latin species name“natans“, meaning “swimming” or “floating.”
  
• Food Preference: The fish feed on plankton, which they filter from the water column while hovering above the coral. They have been observed picking up small food particles.
  
• Group behavior: Bryaninops natans lives in small to large groups, often in schools of 8 to 10 individuals, or even up to 100 individuals.
  
• Depth and habitat: Although found mainly in shallow waters (7-12 meters) associated with Acropora coral, there are also observations at greater depths (21-27 meters).
  
• Color variation: The color of live specimens may vary, especially the intensity of pink and red markings. The internal bands may be more intense or less visible, depending on conditions.
  
• Taxonomic confusion: The documents show that there has been confusion in the past about the taxonomic classification of B. natans, and the genus Tenacigobius has been considered synonymous.

Conclusion

Bryaninops natans, the Purple-eye Goby, is a small, peace-loving fish with a distinctive hovering behavior above Acropora coral. Although they are relatively easy to care for in a properly set-up aquarium (at least 50 gallons for a group of six), they do require a specific environment with adequate current and a group size of at least six specimens to exhibit their natural behavior. It is important to feed them with fine, suspended food. Additional research is needed to confirm their reef safety with certainty.

The Purple-eye Goby is an interesting fish for advanced beginners. Their unique floating behavior and the need for a specific group size make them unsuitable for absolute beginners. Their shy nature requires a quiet environment. Available information on breeding is limited, which makes their suitability for breeding in an aquarium uncertain. More research on their diet and specific needs in captivity is desirable to ensure their successful long-term care.

Video

Author

John de Lange

Copyright images

Divemecressi
Rickard Zerpe – CC BY 2.0
Klaus Stiefel – CC BY-NC 2.0
Doug Anderson

Resources

• Michiels, N. K., Anthes, N., Hart, N. S., Herler, J., Meixner, A. J., Schleifenbaum, F., … & Wucherer, M. F. (2008). Red fluorescence in reef fish: A novel signalling mechanism?. BMC ecology, 8(1), 16. http://dx.doi.org/10.1186/1472-6785-8-16
• Suzuki, T., Bogorodsky, S. V., & Randall, J. E. (2012). Gobiid fishes of the genus Bryaninops from the Red Sea, with description of two new species and two new records. Zootaxa, 3170(1), 1-20. http://dx.doi.org/10.11646/zootaxa.3170.1.1
• Herler, J. (2007). Microhabitats and ecomorphology of coral- and coral rock-associated gobiid fish (Teleostei: Gobiidae) in the northern Red Sea. Marine Ecology, 28(1), 1-14. http://dx.doi.org/10.1111/j.1439-0485.2007.00165.x
• Larson, H. K. (1985). A revision of the gobiid genus Bryaninops (Pisces), with a description of six new species. The Beagle: Records of the Museums and Art Galleries of the Northern Territory, 2(1), 57-93. http://dx.doi.org/10.5962/p.262826