The False Freshwater Sole tail is fused with the rest of the fins giving it the tongue-like shape!
The Freshwater Sole Brachirus panoides is a freshwater member of the Soleidae Famiiy of “true soles” that occurs worldwide. Most sole fish species live in the ocean but a few smaller ones inhabit fresh water or brackish water. It is also called the False Freshwater Sole and False Pan Sole, as well as Tonguefish, Pan Sole, and Hogchoker Sole.
Sole fish are members of the Pleuronectiformes order of laterally compressed fish known as “flatfish”. Other flatfish are Flounders, Tonguefish, American soles, and food fishes like Halibut.
Sole fish are sometimes referred to as flounders because they share a flat and somewhat rounded appearance. Sometimes they are also called tonguefish due to similar ‘tongue-like’ characteristics. However both these names are not accurate for sole fish. Both Flounders and Tonguefish have distinct anatomical features and are classified in distinct and separate families. Flounders are mostly saltwater fish, and are a more distant relative to the sole fish. True Soles on the other hand, are closely related to both the American Soles of the Achiridae family and the Tonguefish of the family Cynoglossidae, also called “tongue soles”.
The False Freshwater Sole makes for a very unique looking and interesting fish to have in your tank. The intriguing anatomy of sole fish is that they are flattened, or compressed laterally. They literally swim on their left side on the bottom of their environment. After they are born, their left eye migrates over to the right side and points up, leaving the left side or ‘bottom’ side blind. The False Pan Sole also has some characteristics of the Tonguefish. Like Tonguefish their fins are fused with the tail, edging their entire body and giving them a “tongue”‘ like appearance.
This Freshwater Sole is an interesting species that will do quite well in an aquarium if given the correct environment. However don’t jump into getting one of these fish unless you are ready to dedicate time and energy to its care. These are picky, slow moving fish when feeding, and you have to make sure they get their fill. They will normally feed late at night when the other fish aren’t interested in eating.
For Information on keeping freshwater fish, see:
Freshwater Aquarium Guide: Aquarium Setup and Care
- Kingdom: Animalia
- Phylum: Chordata
- Class: Actinopterygii
- Order: Pleuronectiformes
- Family: Soleidae
- Genus: Brachirus
- Species: panoides
- Aquarist Experience Level: Advanced
- Size of fish – inches: 7.9 inches (20.07 cm)
- Minimum Tank Size: 55 gal (208 L)
- Temperament: Peaceful
- Aquarium Hardiness: Moderately hardy
- Temperature: 74.0 to 82.0° F (23.3 to 27.8° C)
- My Aquarium – Enter your aquarium to see if this fish is compatible!
Habitat: Distribution / Background
The Freshwater Sole Brachirus panoides was described by Cuvier in 1829. They are found in Southeast Asia from Thailand to Indonesia. The species is not listed on the IUCN Red List. However there is some concern about population declines caused by dragger nets, but not to the point of actually causing a severe decrease in population.
Other common names B. panoides are known by are False Freshwater Sole, False Pan Sole, and Tonguefish. The additional names of Pan Sole and Hogchoker Sole are used for this fish, as well as two other species that are occasionally imported. The species Brachirus pan, imported from Bangladesh and India, Is referred to as True Pan Sole and Pan Sole. The species, Trinectes maculatus, an American Sole which originates in North America, is called the Hogchoker Sole. The T. maculatus is very similar to the False Freshwater Sole in overall appearance, but these two can be told apart by their body shape and tail.
False Pan Sole are seen on the bottom of estuaries and in the lower courses of rivers. These fish tend to live in pure freshwater as well as brackish water. They will normally stay covered with sand or mud most of the day and hunt at night. Soles camouflaged themselves in a combination of colors that match their surroundings, making them very hard to spot. They will feed on benthic invertebrates in nature.
Several freshwater or brackish water sole fish occasionally available to the aquarist are:
- True Soles – Family Soleidae
The True Soles live in fresh water and saltwater environments. They have a similar body shape to the Tonguefish, but are often more rounded, and they have a small rounded head. The dorsal fin starts above or before eyes. Both dorsal and anal fins extends back to the caudal fin, and can be fused with it or not. They may or may not have pectoral fins, and there are no fin spines.
True Soles begin life with an eye on each side of the head. But during development the left eye moves around onto the right side of the head. They lie on on their left side (“blind” side) on the bottom of their environment, usually buried in mud.
- False Pan Sole Brachirus panoides – prefers freshwater or slightly brackish water.
- True Pan Sole Brachirus pan – prefers brackish water.
- Oriental Sole Brachirus orientalis prefers brackish water or saltwater.
- Freshwater Sole Brachirus harmandi is a freshwater species.
- Salt Pan Sole Synaptura salinarumis a freshwater species.
- American Soles – Family Achiridae
The American Soles lives in fresh water and saltwater environments. Their eyes are on the right side, and the lip on this side has a distinctive fleshy rim. The dorsal and anal fins are usually separate from the caudal fin. They may or may not have pectoral fins, and there are no fin spines.
- Hogchoker Sole Trinectes maculatus – prefers brackish water or saltwater.
- South American Lined Sole Achirus lineatus – prefers brackish water or saltwater.
- Tonguefish – family Cynoglossidae
The Tongue Soles live in fresh water and saltwater environments. Their bodies are shaped like a roundish, elongated arrowhead tapering into a long tail fin and they have a shovel shaped head on the front. Their eyes are both on the left side of their body. Distinguishing features are a long hook on the snout overhanging the mouth, and lacking pectoral fins and a pelvic fin.
- Asian Tongue Soles Cynoglossus spp. various species, some are strictly freshwater.
- Scientific Name: Brachirus panoides
- Social Grouping: Pairs
- IUCN Red List: NE – Not Evaluated or not listed
The False Freshwater Sole or False Pan Sole can reach up 7.9 inches (20 cm) and its life span is up to 15 years. The body color is a rich orangish brown mottled with black spots and blotches. They are compressed laterally and they swim on their side on the bottom of their environment. After birth, their left eye migrates over to the right side and points up, leaving the other side or ‘bottom’ side blind. Their anal fins are fused with the other fins and edge their entire body, thus giving them a ‘tongue’ like appearance.
- Size of fish – inches: 7.9 inches (20.07 cm)
- Lifespan: 15 years
Fish Keeping Difficulty
The False Pan Sole is not a fish for beginners. There are a variety of species of Freshwater sole commonly available and they can be difficult to tell apart. It can be hard to know what fish you have, which makes it difficult to know. the exact conditions the fish needs. If you don’t know, keeping the aquarium slightly brackish, at a specific gravity of about 1.0005 is your best bet. The truly freshwater species can easily tolerate a low specific gravity so even if you happen to misidentify a freshwater species as a brackish water one, no harm will be done.
Water conditions are fairly easy to manage, but the biggest issue is getting them enough food. They are nocturnal hunters and will not eat at all during the day. They also tend to be slow moving. By the time they start to eat, the food has often already been consumed by the other fish. They also prefer live foods, which can be expensive and is can introduce disease to the tank.
- Aquarium Hardiness: Moderately hardy – Hardy if able to properly feed.
- Aquarist Experience Level: Advanced – Best for experienced keepers due to the difficulty feeding these fish.
Foods and Feeding
Since they are carnivores, the False Freshwater Sole will eat all types of protein foods. Feed a diet of live or fresh frozen foods such as brine shrimp, mysids, black worms, earthworms or bloodworms. Some specimens, once comfortable in their new home will accept catfish pellets and chunks of prawn or white fish. Some may also eat a bit of algae, but it will be very little and they are not scavengers. They are not aggressive feeders so food may have to be poured directly on top of them to make sure they get enough to eat. They will also eat tiny fish so make sure any tank mates are too large to be able to fit into their mouths.
For best success feed them at night when they are normally ready to hunt and their natural instincts are intact. It is very important to monitor how much they actually consume, and to make sure that the animates to not take their food.
- Diet Type: Carnivore
- Flake Food: No
- Tablet / Pellet: Occasionally
- Live foods (fishes, shrimps, worms): Most of Diet
- Vegetable Food: Some of Diet – Some species may eat a bit of algae, but it will be very little and they are not scavengers.
- Meaty Food: Most of Diet
- Feeding Frequency: Daily
These fish do not need a lot. Once you figure out their needed water conditions the tank care is fairly simple. If you don’t know what species you have, keeping the water slightly brackish is a safe bet for all species. A specific gravity of around 1.005, is fine and the freshwater species can handle this little bit of salt. Provide weekly partial water changes as needed, generally about 25 – 50%. Water changes can be quite variable, depending on salinity, tank size, and stocking density (bio-load). For example, a saltwater aquarium generally needs about twice as much water changed out as a freshwater aquarium.
- Water Changes: Weekly – Do water changes as needed, generally about 25 – 50% weekly.
The False Freshwater Sole is sometimes found in the mouths of rivers where the waters empty into the ocean, so they will do well in either fresh or brackish water tanks. They do require a fairly large tank of at least 55 gallons, and a high quality canister filter. These fish are sensitive to low oxygen levels and require air stones to keep the oxygen level high.
They spend virtually all of their time on the bottom so special care needs to be given to where they live. To feel secure, they should be able to bury themselves which means that very fine gravel or sand is the substrate of choice. It is not unusual to see only a pair of eyes poking up through the sand. Adding some rock or wood decor is fine, but should be kept to the back and sides of the tank so they have an open, uncluttered area for burrowing.
- Minimum Tank Size: 55 gal (208 L)
- Substrate Type: Sand
- Lighting Needs: Low – subdued lighting
- Temperature: 74.0 to 82.0° F (23.3 to 27.8° C)
- Range ph: 7.0-8.0
- Hardness Range: 7 – 10 dGH
- Brackish: Sometimes – They will do well in either fresh or brackish water tanks.
- Water Movement: Weak
- Water Region: Bottom – They will spend most of their time on the bottom, although they may occasionally stick to the sides of the tank.
The False Pan Sole is peaceful, but choose tank mates that are too large to fit into its mouth. This fish is not aggressive but since it is a predator care is needed when choosing tank mates. The other concern when keeping them in a community tank is making sure they get enough food. They are not aggressive eaters and are slow to find food. Avoid fishes like loaches and catfish, but daytime active fish like livebearers and gobies are good tank mates.
- Venomous: No
- Temperament: Peaceful – Peaceful, but a predator that will eat fish that fits in its mouth.
- Compatible with:
- Same species – conspecifics: Yes
- Peaceful fish (): Monitor – Tank mates most not be small enough to fit in their mouth.
- Semi-Aggressive (): Monitor
- Aggressive (): Threat
- Large Semi-Aggressive (): Threat
- Large Aggressive, Predatory (): Threat
- Monitor – Tank mates most not be small enough to fit in their mouth.
- Shrimps, Crabs, Snails: Threat – is aggressive – They feed on benthic invertebrates in nature.
- Plants: Safe
Sex: Sexual differences
Breeding / Reproduction
Has not been bred in captivity. In their native environment they are pelagic spawners and the eggs are non-adhesive.
- Ease of Breeding: Unknown
These fish are very sensitive to low oxygen concentrations in their water, but are very long lived in the right environment. That being said the mortality rate is very high in most home aquariums. This has nothing to do with the health of the fish, but the inability of the fish keeper to make sure the False Freshwater Sole is getting its share of food. This fish normally dies of starvation.
As with most fish the Freshwater Sole are prone to skin flukes, parasitic infestations (protozoa, worms, etc.), ichthyobodo infection, parasitic infestations (protozoa, worms, etc.), bacterial infections (general), and bacterial disease. Anything you add to your tank has the possibility of bringing disease to your tank. Not only other fish but plants, substrate, and decorations can harbor bacteria. Take great care and make sure to properly clean or quarantine anything that you add to an established tank so not to upset the balance.
These fish are hardy and disease is not usually a problem in a well maintained aquarium. That being said there is no guarantee that you won’t have to deal with health problems or disease. Because these fish eat live food, disease can be passed to them from their foods. Make sure to quarantine live food before feeding.
A good thing about the Freshwater Sole is that due to their resilience, an outbreak of disease can often be limited to just one or a few fishes if you deal with it at an early stage. When keeping more sensitive types of fish, it is common for all fishes to be infected even before the first warning signs can be noticed. The best way to proactively prevent disease is to give your fish the proper environment and give them a well balanced diet. The closer to their natural habitat the less stress the fish will have, making them healthier and happy. A stressed fish is more likely to acquire disease..
Knowing the signs of illness, and catching and treating them early makes a huge difference. It is recommended to read up on the common tank diseases. For information about freshwater fish diseases and illnesses, see Aquarium Fish Diseases and Treatments.
Although commonly available, the False Freshwater Sole or False Pan Sole is not a fish that many stores will carry on a regular basis. It is definitely a candidate for a special order.
- Animal-World References: Freshwater Fish and Plants
- Animal-World References: Marine and Reef
- Scott W. Michael, Reef Fishes Volume 1, T.F.H Publications inc., 2001
- Dr. Warren E. Burgess, Dr. Herbert R. Axelrod, Raymond E. Hunziker III, Dr. Burgess’s Atlas of Marine Aquarium Fishes, T.F.H Publications inc., 1990
- Neale Monks, Brackish Water Fishes: An Aquarist’s Guide to Identification, Care & Husbandry, TFH Publications, 2006
- Neale Monks, Freshwater flatfish, order Pleuronectiformes, Brackish Water Aquarium FAQ, 2007
- Brachirus panoides (Bleeker, 1851), Fishbase.org