Gymnothorax polyuranodon - Maipenrai Aquarium tropical fish exporter
There is one species of moray eel that is notable for its ability to live in freshwater environments, though it is quite rare and unique compared to other moray eels. Gymnothorax polyuranodon also known as the freshwater moray, is known to inhabit brackish and freshwater environments in Southeast Asia, particularly around rivers, estuaries, and coastal mangrove areas.
While most Gymnothorax species are strictly marine, Gymnothorax polyuranodon has adapted to live in environments where salinity can fluctuate. This species is more commonly found in areas where freshwater and saltwater mix, making it semi-freshwater or brackish rather than truly living in freshwater like some other eel species (like Anguillidae, the true freshwater eels).
The ability to survive in low-salinity environments sets Gymnothorax p. apart, but it is still more comfortable in areas with some level of salt in the water. Like other moray eels, it tends to stay hidden in rocky or submerged areas and preys on small fish and invertebrates.
Gymnothorax p., also known as the freshwater moray, primarily inhabits estuarine and brackish water environments in Southeast Asia. These eels are often found in river mouths, mangrove areas, and coastal habitats where freshwater and saltwater mix, creating conditions of varying salinity.
Although they are adapted to brackish and sometimes freshwater environments, they still require a certain level of salinity to thrive. Gymnothorax polyuranodon tends to stay in sheltered areas such as rocky crevices, mudflats, or mangrove roots where they can hide during the day and hunt for food at night. The presence of dense vegetation or complex underwater structures provides excellent cover for them, as they prefer staying hidden from predators.
In these habitats, they primarily feed on small fish and invertebrates, hunting at night like many other moray species. While they are capable of surviving in freshwater, their ideal environment is one with a mix of both freshwater and saltwater, where they can easily adjust to changing conditions.
Their ability to tolerate a range of salinities sets them apart from the majority of other Gymnothorax species, which are strictly marine.
Keeping Gymnothorax p. (the freshwater moray eel) in an aquarium can be an exciting challenge, given its unique habitat requirements and the fact that it’s adapted to brackish or semi-freshwater environments. While it's not commonly kept in home aquariums due to its specific needs, it is possible with the right setup and care. Here are some key factors to consider if you're thinking about keeping this eel in an aquarium:
1. Tank Size
Gymnothorax polyuranodon can grow to a length of about 1 meter (3 feet) or more, so you'll need a relatively large aquarium. A tank of at least 75-100 gallons (approximately 280-380 liters) would be ideal, as this allows ample space for the eel to roam and hide. Since these eels are quite active, the larger the tank, the better.
2. Water Parameters
As a brackish water species, Gymnothorax p. requires specific water conditions:
- Salinity: Maintain a salinity level in the range of 1.005–1.015 specific gravity (SG), which is typical for brackish water.
- pH: Keep the pH between 7.5 and 8.5, slightly alkaline, which is common for brackish environments.
- Temperature: A water temperature of around 24-28°C (75-82°F) is ideal, which simulates the warm waters of estuaries and coastal areas.
- Water quality: Make sure the water is clean, well-filtered, and well-oxygenated. Regular water changes are important to keep ammonia and nitrite levels low.
3. Tank Setup
These eels love hiding in crevices, so you'll want to replicate the rocky or mangrove-like environment that they would naturally inhabit.
- Rockwork and caves: Provide plenty of hiding spaces with rocks, caves, and tunnels where the eel can feel safe. They are nocturnal and spend a lot of time hiding during the day.
- Substrate: A fine substrate, like sand or small gravel, is preferable. They like to burrow into the sand, especially when feeling stressed or resting.
- Plants: If you want to add live plants, choose hardy, brackish-tolerant species. Mangroves or salt-tolerant grasses might work well.
4. Diet
Gymnothorax p. is a carnivorous predator, so it will need a diet that consists of:
- Frozen or live food: Offer a variety of foods such as frozen or live fish, shrimp, squid, and other meaty foods. Some aquarium keepers feed them chopped seafood or pieces of fish.
- Feeding technique: Because of their natural hunting behavior, you might need to use tongs or feeding sticks to deliver food to the eel, as they tend to be shy and might not always eat from the surface.
5. Tankmates
While Gymnothorax p. can be kept with other species, it's best to choose peaceful, non-aggressive tankmates that won’t disturb the eel. It may not do well with very small fish, as it might try to hunt them. Larger, peaceful fish such as other brackish-water species or certain invertebrates (like larger crabs or snails) can work as companions.
6. Behavior and Maintenance
- Nocturnal nature: Since these eels are mainly nocturnal, you’ll likely see them more during the evening or night. They can be shy during the day, retreating into their hiding spots.
- Escape artists: Moray eels are known for their ability to squeeze through small openings, so be sure your aquarium has a secure lid to prevent escapes.
7. Challenges
- Brackish water maintenance: Maintaining the right salinity and water quality can be challenging for aquarium keepers who are new to brackish water setups. You'll need to regularly monitor and adjust salinity, pH, and temperature.
- Size: Due to their potential size and activity level, larger tanks are necessary, which may be an investment in both space and equipment.
8. Breeding
Breeding Gymnothorax p. in captivity is not commonly done, but it's possible under the right conditions. However, creating the right environment for spawning is tricky since it involves maintaining proper salinity gradients and potentially replicating the natural conditions of brackish water systems.
Final Thoughts
While Gymnothorax polyuranodon can be a fascinating addition to a brackish water aquarium, they do have specialized care requirements. A properly set up brackish aquarium with the right water parameters, hiding spaces, and food sources will help create a comfortable environment for this eel. If you're new to brackish tanks, it might take some time to get the water conditions just right, but once established, they can be an intriguing and unique species to observe!
