The Freshwater Lionfish is actually much more of a brackish water fish… or even saltwater!

The Freshwater Lionfish Batrachomoeus trispinosus is a most interesting fish that can be kept in the brackish water aquarium. These unusual fish are found in the muddy bottoms of mangrove estuaries and coastal waters. It is actually more of a marine fish, but because in nature it spends a good deal of time where salt waters are mixed with fresh, it is more adaptable to lower salinity levels than other marine animals.

Its common name in Australia is the Three-spined Frogfish. No one is quite sure how it received the common name of Freshwater Lionfish. They are not related to the saltwater Lionfish, sub-family Pteroinae, and fortunately they are not venomous like those saltwater Lionfish. Probably someone with an overactive imagination couldn’t pronounce “Batrachomoeus trispinosus” and needed to call them something! They are members of the Batrachomoeus genus, which are non-venomous Toadfish.

The Freshwater Lionfish is truly an oddball fish, and rather grumpy. The names of Toadfish, Frogfish and even Stonefish give a good impression of what this fish looks and acts like. It sits very still and looks much like a camouflaged brown lump or stone, thus the name Stonefish. The broad head and large mouth are very frog-like. It also feeds very much like a frog or toad would, waiting patiently until its food comes within range and then gulping it down quickly.

The members of the Toadfish family, Batrachoididae, received their name because most of them can make a croaking sound when they are pestered or the males are courting females. It is unlikely that your pet will make this sound but you never know. Some aquarists have reported their fish grunting loudly when fellow inhabitants swim by, giving their tank mates quite a scare and making them race out of the area.

The Freshwater Lionfish gets to be quite large, reaching almost 12 inches (30 cm) in length. But despite its large size, it really doesn’t need a large tank because it is quite still most of the time. It is camouflaged to blend in with its surroundings. It is peaceful, but it is a predator. Choose tank mates that are too large to fit into its cavernous mouth.

Scientific Classification


    Freshwater Lionfish – Quick Aquarium Care

    Aquarist Experience Level:Advanced
    Aquarium Hardiness:Moderately hardy
    Minimum Tank Size:40 gal (151 L)
    Size of fish – inches11.8 inches (29.97 cm)
    Temperature:72.0 to 82.0° F (22.2 to 27.8&deg C)

    Habitat: Distribution / Background

    The Freshwater Lionfish Batrachomoeus trispinosus was described by Günther in 1861.They are a common species found throughout the Indo-West Pacific; northwestern Australia, Thailand, Indonesia, Papua New Guinea, the Arafura Sea, and the Mekong delta. The species is not listed on the IUCN Red List.

    Most species seen in the aquarium fish trade are exported from Thailand. Its common name in Australia is the Three-spined Frogfish. Other common names these fish are known by include Freshwater Stonefish, Freshwater Frogfish, Freshwater Toadfish, Threespine Toadfish, Broadbent’s Frogfish, Estuarine frogfish, Threespine Frogfish, and Toadfish.

    These toadfish inhabit trawling areas of coastal waters and the muddy bottoms of mangrove estuaries, as well as reefs. In the wild the diet of toadfish is quite varied, including such items fish, crabs, shrimp, octopuses, bivalves, snails, sand dollars, urchins, and polychaete worms.

    • Scientific Name: Batrachomoeus trispinosus
    • Social Grouping: Solitary
    • IUCN Red List: NE – Not Evaluated or not listed


    The Freshwater Lionfish is quite large, reaching almost 12 inches (30 cm) in length. The head is about a third of its length, and it has a big mouth. There are spines in its skin. These can cause pain if they are brushed against with your hand. Though this isn’t really a threat, if a person is prone to allergic reactions they should be cautious. The coloring is a dark mottling of browns allowing it to blend into the environment. It sits motionless, looking much like a camouflaged brown lump, or stone, thus the name Freshwater Stonefish.

    • Size of fish – inches: 11.8 inches (29.97 cm)
    • Lifespan: 20 years

    Fish Keeping Difficulty

    They are actually pretty easy to care for and will be comfortable in a variety of water conditions. Yet although they are called Freshwater Lionfish, they will not be long lived in strictly fresh water. The really need to be kept in either a brackish water aquarium, or even a saltwater environment. These fish live in freshwater at low tide, that turns to brackish and then at high tide, to saltwater. Feeding can be difficult as these fish prefer live foods that swim by them. They won’t take flake or pellet foods, and they need to learn to eat dead/ frozen foods. This takes patience, but can usually be accomplished with a feeding stick.

    • Aquarium Hardiness: Moderately hardy
    • Aquarist Experience Level: Advanced

    Foods and Feeding

    The Freshwater Lionfish are carnivores, a predator. In the wild they feed on live crustaceans and fish. In the aquarium feed a variety of foods including bloodworms, earthworms, river shrimp and crayfish. Some fish foods that you can offer include tilapia, rainbow trout, pollack, and cockles. Prawns and shrimp can be used in the short term to get your fish eating.

    This fish relies on camouflage and stealth to get a meal so if their prey doesn’t swim directly in front of them, they may not get enough to eat. Using a feeding stick, aquarium tongs, or forceps to hold foods in front of their mouth is a good way to make sure that it is getting enough to eat. It may take awhile to get one to feed so be patient. Be careful not to overfeed these rather sedentary fish. Provide just enough so that the belly fills out slightly but doesn’t look inflated.

    Some varieties of live fish and saltwater invertebrates are not recommended, at least not for the long term. These include goldfish and guppies, as well as mussels, shrimps, prawns and at least some types of squid. With Goldfish and guppies there is the risk of introducing parasites. Also, these fish and these invertebrates are rich in an enzyme called thiaminase. Thiaminase metabolizes or breaks down vitamin B1 which over the long term can cause severe health problems. The fish listed above are thiaminase-free foods.

    • Diet Type: Carnivore
    • Flake Food: No
    • Tablet / Pellet: No
    • Live foods (fishes, shrimps, worms): Most of Diet
    • Meaty Food: All of Diet
    • Feeding Frequency: Weekly

    Aquarium Care

    This species is best suited for a saltwater or brackish water tank. It can only be kept in fresh water for a short time, but it cannot be permanently maintained in freshwater and live. Acclimate them to a brackish tank slowly, over a period of about a week. They must have a minimum specific gravity of at least 1.005, but a heavy brackish water of 2.5 % to 3% salinity density (specific gravity 1.020-1.024) is suggested for the long term.

    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.

    Aquarium Setup

    The Freshwater Lionfish needs a brackish water or saltwater environment. It cannot be maintained in freshwater as it will not live for long. They must have a minimum specific gravity of at least 1.005, and up to 1.024. Provide a minimum tank size of 40 gallons or more for a juvenile. Larger fish will need much more room with 100 gallons or more being best.

    This species will spend all of its time on the bottom of the tank. A gravel substrate along with rock caves to provide some hiding cover is recommended to keep it in good condition. You can also provide some areas of dense vegetation. They like to be able to camouflage themselves as much as possible to feel safe. A good canister filter that makes a moderate current will be appreciated by this fish.

    • Minimum Tank Size: 40 gal (151 L) – Adult Three-spined Frogfish will need 100 gallons or more.
    • Suitable for Nano Tank: No
    • Substrate Type: Large Gravel
    • Lighting Needs: Low – subdued lighting
    • Temperature: 72.0 to 82.0° F (22.2 to 27.8&deg C)
    • Range ph: 7.8-8.5
    • Hardness Range: 7 – 10 dGH
    • Brackish: Yes
    • Water Movement: Moderate
    • Water Region: Bottom – The Freshwater Lionfish will spend all of it time on the bottom.

    Social Behaviors

    Choose tank mates that are too large to fit into its cavernous mouth. This fish is not at all aggressive but since it is a predator with a very large mouth, considerable care is needed when choosing tank mates. They will stay secluded under cover during the day, though may come out at night. As they become comfortable and learn their feeding regime, they may start to venture out when the lights are on.

    • Venomous: No – Though not venomous, there are spines in its skin that can cause pain if brushed against with your hand.
    • Temperament: Peaceful – Peaceful, but a predator that will eat any fish that fits in its mouth.
    • Compatible with:
      • Same species – conspecifics: Yes
      • Peaceful fish (): Monitor – Must be large enough to not be considered food.
      • Semi-Aggressive (): Monitor
      • Aggressive (): Monitor
      • Large Semi-Aggressive (): Monitor
      • Large Aggressive, Predatory (): Monitor
      • Monitor – Must be large enough to not be considered food.
      • Shrimps, Crabs, Snails: Threat – is aggressive – Crustaceans are part of its natural diet.
      • Plants: Safe

    Sexual differences


    Breeding / Reproduction

    The Freshwater Lionfish has not been bred in an aquarium.

    • Ease of Breeding: Unknown

    Fish Diseases

    As with most fish the Freshwater lionfish 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 Lionfish 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.


    The Freshwater Lionfish is commonly available. They are also called the Three-spined Frogfish, Freshwater Toadfish, Freshwater Frogfish, and Freshwater Stonefish.


   (Image Credit: Dinh D. Tran, FiMSeA, Wikimedia Commons CC BY-SA 3.0 Unported)