Lionfish Care Sheet | PetMD

Lionfish Species Overview

Lionfish are a group of eye-catching saltwater fish known for their zebra-striped bodies and long dorsal spines. This care sheet outlines basic care needs for a variety of pet lionfish species, including: 

• Dwarf zebra lionfish 

• Fuzzy dwarf lionfish

• Antennata lionfish 

• Volitan lionfish 

• Radiata lionfish 

• Fu Manchu lionfish 

• Mombasa lionfish 

Lionfish have venomous dorsal spines that can deliver a painful sting. While lionfish stings usually aren’t fatal, some people are allergic to the sting’s venom. 

Lionfish stings can lead to a variety of symptoms, such as swelling, redness, pain, shortness of breath, and numbness. Anyone stung by a lionfish should monitor their symptoms and consult a medical professional for help. 

Though visually stunning, lionfish are considered an invasive species in the Caribbean Sea and along the East Coast of the United States. Increasing lionfish populations have disrupted food chains in local marine ecosystems. For this reason, lionfish are illegal to own in the state of Florida.

Lionfish are not very active swimmers and are not considered an aggressive species. However, they may try to eat other fish and marine invertebrates that can fit into their wide mouths. 

Lionfish Characteristics 

Lionfish Supply Checklist

To keep a pet lionfish happy and healthy, pet parents should have these basic supplies on hand: 

Lionfish Habitat

Choosing the Right Enclosure 

At a minimum, a single juvenile pet lionfish needs a 29-gallon tank or larger. Pet parents will need to increase the size of their tank as their fish grows.  

A single adult pet lionfish from a smaller species, including dwarf lionfish, should be housed in at least a 55-gallon tank. Larger species, like the Volitan, can reach lengths of over 15” in adulthood and will need at least a 120-gallon aquarium when fully grown. 

All aquariums must be secured with a fitted lid or canopy to prevent your pet fish from attempting to escape and getting injured. Always provide the largest habitat possible. 

Selecting Tankmates 

While lionfish are generally solitary, some species can be housed together in small groups of other lionfish if all the fish are around the same size and the aquarium is large enough. Fu Manchu lionfish are highly aggressive with each other and should only be kept one Fu Manchu to a tank. 

Lionfish can live harmoniously with other species of saltwater fish that are of similar size or larger, including: 

• Groupers 

• Large marine angelfish 

• Foxface/rabbitfish 

• Butterflyfish 

• Tangs 

Pet lionfish should not be housed in the same aquarium as slow-moving or small tank mates, including:

Lionfish are carnivorous and may try to eat any tank mates that are small enough to fit into their wide mouths.  

New tank mates must be introduced to an aquarium gradually, and pet parents should remember that their tank’s ammonia, pH, and nitrate levels will change when a new fish is introduced. These parameters need to be monitored carefully after adding new fish.   

Fish should not be kept in overcrowded aquariums, as these conditions often lead to stress and disease in the tank. 

Filtration 

A filter system is an essential addition to any aquatic habitat. In addition to keeping tanks clean, filters remove harmful toxins like ammonia from the aquarium’s water and add oxygen to the water so fish can breathe.   

Power filters (also known as “hang-on-back” filters) and external canister filters are recommended because they offer effective mechanical, biological, and chemical filtration and do not take up any space inside an aquarium. Lionfish prefer water with slow to moderate circulation. 

Tip: An aquarium’s filter should be powerful enough to process all the water in the tank at least four times an hour. For example, a 20-gallon tank should ideally have an aquarium filter with a flow rate that’s at least 80 gallons per hour (GPH). If only a 50 or 100 GPH filter is available, pet parents should always size up and purchase the 100 GPH option.  

Water Health  

Pet parents should test their aquarium’s water regularly to ensure its pH, ammonia, nitrate, and nitrite levels are stable and within a safe range. An aquarium test kit can be used to measure key water parameters quickly and accurately. A protein skimmer can also be used to maintain the tank’s water quality. 

As a saltwater species, pet lionfish need salt in their aquarium to survive. When setting up their tank, add small amounts of marine salt to their lionfish’s habitat until the water’s specific gravity is between 1.020 and 1.025. The specific gravity reading should not change more than +/- 0.001 in 24 hours. A hydrometer or refractometer (salt level tester) should be used to measure the salt concentration and specific gravity of the aquarium’s water. 

Temperature 

Lionfish prefer warm water temperatures from 74 to 80 F. The water’s temperature should not fluctuate more than 2 degrees up or down in 24 hours.  

Pet parents should install an aquatic heater that’s controlled with a thermostat in their aquarium to keep the water’s temperature in the ideal range. An aquarium thermometer should be used to check the tank’s water temperature daily. 

When selecting a heater for their tank, pet parents should keep a few things in mind: 

• Some modern heaters have built-in thermostats, while others need to be paired with a thermostat that’s purchased separately. 

• As a rule of thumb, aquarium heaters need between 2.5 and 5 watts of power for every gallon of water in a tank. This means that a 10-gallon tank needs a 25- to 50-watt heater. 

Larger aquariums with a tank volume over 50 gallons may need two small heaters, placed on opposite sides of the tank, to prevent cold spots from developing in the water. 

Decor and Accessories 

Substrate

Lionfish aren’t strong swimmers and tend to “hop” along the floor of their tank. The bottom of a pet lionfish’s tank should be lined with 1–2 inches of a soft substrate, such as aragonite sand or crushed coral. 

Avoid gravel—it can be too rough for a lionfish’s delicate fins. 

Rocks and Hiding Decor

Most lionfish species are crepuscular, meaning they are most active around dusk and dawn. As a result, they need plenty of places to hide and rest during the day. Use rocks, caves, and crevices to create safe hiding places in a lionfish’s tank. 

Lionfish Cleaning and Maintenance

Pet parents can maintain the condition of their lionfish’s tank by performing routine water changes (no more than 10–25% of the aquarium’s total water volume) every two to four weeks. Uneaten food should be removed from an aquarium daily with the help of a fine mesh net. 

Draining and replacing the aquarium’s entire water volume should be avoided, as doing so will remove the beneficial bacteria in the tank that keep the habitat’s ecosystem healthy. 

Most aquariums need a full cleaning once a month, depending on the number of fish/invertebrates in the tank. Follow these step-by-step instructions on how to clean an aquarium.

Lionfish Diet and Nutrition

Lionfish are primarily carnivorous and should be fed a varied diet of frozen meaty foods (including silversides, krill, and squid) and freeze-dried krill. To stay healthy, pet lionfish need variety in their diet and should not be fed the same food every day. 

Tip: If a pet lionfish is hesitant to eat prepared foods, pet parents may need to start by feeding live foods and gradually transition to frozen food and freeze-dried krill.  

Lionfish need to be fed one to two times per day (depending on size/species) and should not be offered more food than they can consume within 1–2 minutes. Frozen foods must be thawed before feeding. 

Remember: Pet parents should never use a microwave to thaw or warm frozen food, and never offer food that’s still frozen to a pet. Frozen food that is not consumed should never be refrozen for future use, as this encourages bacteria to form in the food. 

Considerations for Lionfish

• After a new fish/invertebrate or new equipment is added to an aquarium, it’s important to test the tank water’s quality once a week for at least two months to ensure that its pH, nitrite, ammonia, nitrate, carbonate, and general hardness levels are in the ideal range.  

• If the tests’ results are safe and consistent after two months, pet parents can decrease water testing to once a month. 

• Water test kits expire and should be replaced yearly.  

Pet parents should monitor their aquarium’s water level and top it off as needed. Before being added to an aquarium, water must be treated with a water conditioner to remove toxic chemicals like chlorine, chloramines, and heavy metals.  

An aquarium’s filter, water temperature, and other equipment should be checked daily to ensure they’re working properly. Filter media should be replaced monthly or rinsed in old tank water during water changes, depending on the water condition and the number of fish/invertebrates in the tank. 

Pet parents should follow the use, care, and maintenance instructions provided by the manufacturer of their filter system.  

Do not use hot water, bleach, or chemicals while rinsing filter media. This will kill the beneficial bacteria that helps keep aquatic habitats safe, clean, and stable.  

Avoid replacing all the filtration media in an aquarium at the same time, as this can also remove beneficial bacteria from the tank. 

Lionfish Veterinary Care

Annual Care

In a properly maintained tank of appropriate size, if you perform your own water quality tests and water changes weekly it is OK to consult with a veterinarian only if you believe there is a problem with your pet lionfish. When having your lionfish assessed, it is best to use a mobile, aquatics-specialized veterinarian who can assess them from within or near their tank, due to difficulties transporting a fish of this size. It can also be dangerous to handle these fish and should only be attempted by trained specialists.

Signs of a Healthy Lionfish

• Bright coloration

• Full range of fin motion, equal on both sides

• Intact fins and spines all the way to the edges with no discoloration

• Regular, upright swim pattern, may not be very active

• Large appetite

When to Call a Vet

• Changes to coloration – particularly becoming dull, or focal spots of change

• White growths/spots

• Gill color changes, usually pale or red

• Lethargic swimming, potentially with an abnormal pattern such as circling, listing to the side, or staying on the top or bottom of the tank

• Receding fin edges with or without discoloration at the edges

• Decreased appetite for more than a day

• Itching

• Rapid breathing, potentially with flared gills

• Presence of lumps/bumps/masses

• Bloated appearance with scales flared outward instead of laying flat

• Bulging eyes, with or without a color change

Common Illnesses in Lionfish

Most lionfish illnesses are secondary to water quality deficiencies. These illnesses can include: