FRESHWATER SOLE (LEPTACHIRUS DARWINIENSIS)
 
Common Name: Freshwater Sole, Darwin Freshwater Sole, Darwin Sole, Freshwater Flounder
Scientific Name: Leptachirus darwiniensis
Family: Soleidae
Origin: Australia
 
SPECIES OVERVIEW
The Freshwater Sole is a fascinating Australian native flatfish and a unique addition to the freshwater aquarium. Unlike typical aquarium fish, the Freshwater Sole has a highly flattened body and spends most of its time resting directly on the substrate.
As the fish develops, both eyes are positioned on one side of the head, allowing it to lie flat against the bottom while remaining well camouflaged. It is an unusual and highly sought-after species for aquarists looking for something different.
 
Freshwater Sole are peaceful and spend much of their time resting on or partially burying themselves in fine substrate. They are primarily nocturnal and can be more active when aquarium lighting is reduced.
 
CARE REQUIREMENTS
Minimum Aquarium Size: 200 Litres
Temperament: Peaceful
Water Level: Bottom Dweller
Diet: Carnivore
Activity: Primarily Nocturnal
Social Behaviour: Can be kept individually
 
WATER PARAMETERS
Temperature: 23–28°C
pH: 7.0–8.0
Hardness: Moderate to Hard
Maintain stable water conditions with good filtration and regular water changes. Avoid sudden changes in temperature or water chemistry.
 
AQUARIUM SETUP
A fine, soft sand substrate is essential for this species. Freshwater Sole naturally spend much of their time resting on the bottom and may partially bury themselves in the substrate.
Avoid sharp gravel or rough substrates that can damage the delicate underside of the fish.
Provide open areas of sand along with some cover and shaded areas. Driftwood and smooth rocks can be used to create additional shelter, but sufficient open substrate should always remain available.
Good filtration and oxygenation are recommended while avoiding excessive water movement across the substrate.
 
DIET & FEEDING
Freshwater Sole are carnivorous and should be offered a varied diet consisting primarily of small aquatic invertebrates.
Suitable foods include:
• Frozen bloodworms
• Frozen Mysis shrimp
• Brine shrimp
• Blackworms
• Small live aquatic invertebrates
• Small sinking carnivorous pellets
Newly introduced specimens can sometimes be reluctant to accept prepared foods. Offering live or frozen foods initially can help encourage feeding before gradually introducing quality sinking foods.
 
FEEDING NOTE
Freshwater Sole are slow and deliberate feeders and can easily be outcompeted by fast-moving tankmates.
Feed after lights-out or during the evening when the fish is most comfortable feeding. Target feeding can be beneficial to ensure the sole receives enough food.
 
TANKMATES
Freshwater Sole are peaceful and can be housed with other peaceful community fish of an appropriate size.
Suitable tankmates include:
• Peaceful Rainbowfish
• Small to medium Tetras
• Gouramis
• Blue-eyes
• Peaceful Gobies
• Corydoras
 
Avoid aggressive, fin-nipping or highly competitive species that may prevent the sole from feeding.
Do not keep them with fish large enough to view the sole as prey.
IMPORTANT INFORMATION
Freshwater Sole are a specialised species and are best suited to experienced aquarists who can provide the correct substrate and feeding conditions.
Their unusual body shape and bottom-dwelling behaviour make them a fascinating addition to an Australian native or specialist freshwater aquarium.
 
The species is native to northern Australia and occurs in freshwater environments. Providing a soft sandy substrate and ensuring the fish receives adequate food are the most important considerations for long-term success.
Freshwater Sole can reach approximately 30 cm in length, so adequate aquarium space should be provided as the fish matures.