Saltwater Lionfish

The Lionfish, Pterois volitans, is an intricately shaped member of the family Scorpaenidae. This family is home to some of the world's most venomous fish species and the Lionfish is certainly not an exception. If possible, you should never attempt to touch or handle a Lionfish since it can give you a painful, venomous sting. The area can ache for several days and sensitive persons can become seriously ill and develop respiratory depression. You can avoid being stung by Lionfish by never reaching into dark crevices and hollows when you snorkel and scuba dive near reefs in areas where they Lionfish live. If you plan on keeping a saltwater Lionfish in captivity, it is important to seek the advice of experienced Lionfish keepers regarding the proper care and handling of Lionfish and how to act if you are stung.

The Lionfish can reach a size of 30-38 centimetres and must therefore be given a really large aquarium if you want to keep it in captivity. It is equipped with 14 delicate pectoral rays that look almost like feathers, and there is also a long “tentacle” that protrudes above eyes. The Lionfish sports a bony ridge that goes across its cheek and the eyes as well as the nose are partly covered by flaps. One of the differences between Pterois volitans and all the other members of the family Scorpaenidae is the fact that the former has 13 dorsal spines while all the others have no more than 12.

The Lionfish is native to the Indo-Pacific, but has today been introduced to several other warm parts of the world by man. Aquarists that grow tired of their pets sometimes release them into the wild, even though this is strongly advised against due to the potential impact on the native ecosystem. There is for instance an established population of Lionfish in Florida which is assumed to hail from aquarium specimens. In rare situations, accidents can also cause Lionfish to escape into the wild. Hurricane Andrew did for instance cause a large beachside aquarium filled with Lionfish to break and the fish was flushed into the ocean off the coast of Florida.

Adult Lionfish are solitary animals that only seek out each other during the breeding period, but juvenile specimens are often found living together in groups. As the fishes mature, each of the will claim its own territory and violently defend it against any other member of its own species, regardless of sex. When Lionfish fights, they try to sting each other with their venomous dorsal spines. Males are even more aggressive than females, especially when competing over suitable mates. As you can see, keeping adult Lionfish together in the same aquarium is not a good idea.

When two male Lionfish meet during the breeding period, the owner of the territory will spread his fins and start swimming back and forth in front of the intruder while pointing the venomous spines forward in an effort to scare him away. If the intruder does not leave, the Lionfish will swim up face to face with him and start trembling and shaking its head. If the intruder is bold enough to stay, the two fishes will soon be engaged in violent attacks where they do their best to bite and sting each other. It is common for Lionfish to try to tear the mouths of each other during territorial disputes.

The Lionfish is chiefly nocturnal and spends the day hiding in crevices and other hollows. As the sun sets, it will leave its shelter and start moving around in a very graceful manner by gently undulating the soft rays found on its dorsal and anal fins. It is common for a Lionfish to have finished eating within less than an hour, but it will still spend the rest of the night out in the open until the sun sets in the morning. 

Freshwater Lionfish

In the aquarium trade, several different species are sold under the common name “Freshwater Lionfish”. These fishes are not related to Pterois volitans and should not be confused with the saltwater Lionfish. A majority of the specimens sold as Freshwater Lionfish are brackish species that will do much better in a brackish aquarium than in a freshwater aquarium. If you want to keep such a species it is therefore recommended to set up a brackish aquarium for it instead of forcing it to live with your freshwater fish. If the brackish fish has been kept in a freshwater aquarium in the pet store, it is important to gradually increase the salinity of the water since a rapid shift can be dangerous for it.

Batrachomoeus trispinosus
This is one example of a fish species commonly offered as Freshwater Lionfish. Other examples of commonly used English names are Threespine toadfish and Estuarine frogfish. If you want to keep this fish, you must provide it with a large aquarium because it can reach a size of up to 30 centimetres. It is a brackish species capable of venturing out into the saltier ocean. Its native habitats are reefs and mangrove estuaries, and it can also be seen quite far offshore. It is most commonly found in shallow regions and requires warm water to thrive. Its geographical range includes the coasts of Australia, Cambodia, Indonesia, Malaysia, Papua New Guinea and Thailand in the Indo-West Pacific Ocean. Batrachomoeus trispinosus is not included in the IUCN Red List of Threatened Species. It has a minimum population doubling time of no more than 1.4 - 4.4 years which makes it quite resilient towards over fishing.

Allenbatrachus grunniens
This species is another brackish and marine species commonly sold as freshwater Lionfish. It is also known under the English name Grunting Toadfish. If you want to keep this fish, you must give it a big aquarium since it can reach a length of 30 centimetres. Its native habitats are the bottoms of the Indo-West Pacific coasts and Allenbatrachus grunniens is especially fond of estuaries with muddy bottoms. Its geographical range is comprised of the coasts of Cambodia, India, Madagascar, Malaysia, Myanmar, Sri Lanka and Thailand. Being a euryhaline species, this so called Freshwater Lionfish is highly adaptable and can survive in a wide range of different salinity levels. It is not believed to be endangered and has not been included in the IUCN Red List of Threatened Species. Just like the lionfish described above, Allenbatrachus grunniens has a minimum population doubling time of 1.4-4.4 years.

Lionfish articles:

Lionfish - An introduction to lionfish.
Fu Manchu Lionfish – Information in how to care for Dendrochirus biocellatus
Dwarf Lionfish – Learn to care for Dendrochirus brachypterus
Zebra Lionfish – A guide to keeping Dendrochirus zebra
Antennata Lionfish – Keeping Pterois antennata
Radiata Lionfish – Learn to care for Pterois radiata
Red Volitans Lionfish – How to keep and breed Pterois russelli
Volatins Lionfish – How to keep, care for and breed Pterois volitans