Pterois Volitans (lionfish)

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Lions are considered “reef safe” with caution. They don’t pose any threat to your sessile inverts but any decorative shrimps, crabs, etc. are likely to become snacks.

Common Names: Volitan, Antennata, Radiata, Dwarf Zebra, Fuzzy Dwarf, Fu Manchu (not an all inclusive list, just the more commonly found names in the hobby species)
Scientific Names: Pterois volitans; Dendrochirus brachypterus, D. zebra
Family: Scorpaenidae
Origin: Found in tropical waters of the Pacific Ocean and the Red Sea at depths of 10-200 feet.
Main Ecosystem: Marine
Salinity: specific gravity 1.020-1.025
Temperament: Peaceful (so long as its tank mates are larger than its mouth) and somewhat shy depending on the fish.
Diet: Carnivore
Care: Water quality and filtration are extremely important. Large filter systems, protein skimmers and large water changes will help to keep ammonia and nitrites low. Be careful to not overfeed. This is a huge part of the water issues with these fishes.

Tank size is a bit of a debate – the bigger the tank the better. I think 30-40 gallons may be appropriate for a Dendrochirus, while an adult Pterois would need no less than 75 gallons, but preferably larger. After all, this fish can attain lengths of up to 12″+. Lionfishes, even though they aren’t very active, need space. They will not thrive without room to move, places to hide where they can feel protected, and large volumes of water to provide adequate oxygen and dilution of waste. The tank should have plenty of liverock or caves to give the lions a place to hide and feel secure.

The lionfish is a carnivorous fish, with a diet consisting of shrimp and fish. When first attaining your lionfish, it may be necessary to start them out on live food to get them to eat and to give them time to get comfortable in their new surroundings. Goldfish are not a good steady diet for lionfish for several reasons. They’re nutritionally deficient, inconvenient, expensive, and may make your lion aggressive. Lionfish can and should be trained to accept better foods. Freshwater prey items will lead to the early death of your lionfish. Ailments caused by FW feeders can include symptoms like vision failure, or the lion may appear to be unable to swallow the old familiar prey as if they have a “lump” in their throat (goiter, swollen thyroid). Chalk it up to dietary deficiencies or inadequacies (like thiamin deficiency induced by a staple of feeder goldfish) taking its toll over time.

You should offer a wide variety of fresh or thawed-frozen meats, and dry or other prepared foods when possible, and gut-loaded live prey if absolutely necessary. It is a myth that they will only eat live food. Once acclimated, they will greedily take frozen, fresh, freeze-dried and prepared rations of all kinds – silversides, krill, shrimp, crabs and even crickets. Avoid oily, greasy foods. When feeding, use a feeding stick or acrylic rod and move the offered food in front of the lion. If it is not accepted, remove the food for another day. Do not worry if your lion goes on a food strike of a few days or longer. If the fish is in good health, it will not suffer ill effects from not eating for a couple days. A new specimen that continues to refuse dead food may need to be weaned with live first. Try guppies or a live bait shrimp placed in front of the lion (when getting my new lions to eat, I used guppies gutloaded with cyclops-eeze). Once the lion is eating, it should easily graduate to non-live foods. Lions need to be fed only once a week – two or three times a week is the maximum. Food size is important. Due to their gulping nature, it is not uncommon for a lionfish to attempt to swallow prey that is too large and die in the process. Lionfish are known for trying to eat fish nearly the same size as themselves, sometimes with success, other times not, so it’s important to consider size of the tankmates before purchasing. The use of a feeding stick is a great tool for training your lion to accept raw foods.

Lionfish tend to hide most of the day under rock ledges. My personal experience indicates that once the fish gets accustomed to you, it will come out more often during daylight hours. They hide during the brightest hours of the day. Lionfish like to rest upside-down in caves. Low lighting is preferred and can be attained by low output fluorescents. If you use metal halides, be sure to offer a dark corner. Glaring lights have been implicated in lion “blindness”.

Lionfishes generally don’t show territorial behavior and will peacefully co-exist with their own kind and other lionfish species. Triggers, puffers and large angels are fish to be watched as potential nipping threats to your lionfish. Lionfish are easy-going with anything they can’t inhale, but they do have remarkably large mouths. Damsels, cardinals, clownfish, shrimps and other non-attached inverts will most certainly be engulfed sooner or later. Also there is the potential that a lionfish may sting their tankmates with their long spines in the crowded confines of an aquarium. Fishes may swim or become spooked into the spines of a lionfish. Erratic swimming, twitching, and sudden death will usually occur within thirty minutes of an effective sting.

Lions are considered “reef safe” with caution. They don’t pose any threat to your sessile inverts but any decorative shrimps, crabs, etc. are likely to become snacks.

Lionfish are venomous, not poisonous. This means that they are toxic to the touch. Poisoning generally comes from ingestion. Lionfish are dangerous to handle alive or dead. The sting of a lionfish must be taken seriously. Swelling, soreness, localized pain, respiratory and cardiac distress and other collateral shock manifestations go with these events. Ringing your local poison center and immersing the site with water as hot as you can tolerate are immediate emergency actions to take. Most sting victims recover quickly without treatment but have to suffer hours of pain that typically leave a lifelong impression and respect for these fish. It should go without saying that you should NEVER take your eyes off these fishes when your hands are in their aquarium. They can “sneak up” on what they perceive as a threat and inflict a painful wound in seconds. Performing routine maintenance like scraping algae is risky since you could bump the venomous spines. A second set of eyes watching your lionfish is a good rule to follow when doing any tank maintenance.

Lionfish have the ability to shed their skin to remove irritants like ich or other parasites. Coughing and shaking are also common during the shedding process.

ph: 8.1-8.4
Temperature: 72-78 degrees fahrenheit
Potential size: The Pterois are considered the “true” full-sized lions. Dendrochirus are more often sold as “dwarf” lions.
Pterois can grow to about a foot and a half; Dendrochirus species are approximately 6 inches in total length when full grown.
Water Region: All levels.
Activity: Most active right before sun up and right before sun down.
Lifespan: 10+ yrs.
Color: Browns, white, black, yellows and reds.
Mouth: Large.
Acclimation: Slow acclimation is best over a period of 1-2 hours. Slowly add tank water every 15-20 minutes.
Breeding: To date, as far as I can find out, there has been no successful captive breeding of lionfish.

Comments: Lionfishes are great fish – just try to remember three points:
1. They are venomous – respect their spines and keep your distance.
2. They are practically indestructible, except for being victims of the aquarist’s tendency to overfeed them, particularly with feeder goldfish.
3. Their water quality quickly degrades with overcrowding and/or inadequate filtration.

The Conscientious Marine Aquarist
reefkeeping online magazine

Filed under Fish Profiles, Saltwater.