Does a Red Lionfish Have a Backbone?

The Red Lionfish (Pterois volitans) has a large pelvic spine along its back, pelvis, and underside. 

Measuring up to 18 inches, this unique species of fish is native to reefs in the Indo-Pacific region. In aquariums, they can grow to between 12 and 15 inches long.

Its bright red and white stripes, spiky fins, and large size make it a popular aquarium fish, even though it is a venomous carnivorous fish that can potentially harm reef ecosystems.

Let’s discuss what the body of a red lionfish looks like, along with other interesting characteristics.

What Does the Body of a Red Lionfish Look Like?

Like all fish, the red lionfish has a spine structure, but it is composed of many bones connected in a distinct pattern. 

There are 13 long, separated spines and 10-11 soft rays in the dorsal region, and 3 spines and 6-7 soft rays in the anal region. Out of the 13 dorsal spines, 10 are usually venomous. 

This, combined with fan-like pectoral fins, serves as the main support structure of the fish, giving it strength and flexibility. 

It also acts as a shock absorber to protect the fish from sudden impacts or changes in pressure.

Red lionfish are considered one of the most splendid-looking species, thanks to their unique spine structure, banded head, and reddish and white vertical bands stretching across the body. 

Their heavy, laterally-compressed body also features two large whiskers (mandibular appendages) on either side of the mouth. 

Rows of dark spots can be seen on the dorsal and anal fins on a clear background. Moreover, fleshy tentacles are located above the eyes and below the mouth. 

6 Interesting Facts about Red Lionfish

  • They Are Venomous

The body of a red lionfish contains acetylcholine (a powerful neurotransmitter and neuromuscular toxin). 

This venom is delivered via the dorsal fins to help defend the fish, and to capture prey. 

Apart from the venom, lightning-fast reflexes and the ability to camouflage help the red lionfish capture prey, which mainly comprises shrimp and smaller fish. 

A sting from this fish can be extremely painful and cause nausea, sweating, breathing problems, and even paralysis in humans. The effects usually last for a few days. 

As soon as its spine punctures your flesh, venom is pushed out along the fish’s backbone. 

It then goes through the channels on both sides of the backbone, rushing through the spine and into your body.  

Although it is rarely fatal, it is advised to seek immediate medical attention if a red lionfish stings you. 

  • They Live in Marine Habitats and Are More Active At Night 

Red lionfish are commonly found in marine habitats spanning the Atlantic waters, from the southeast United States to the Caribbean Sea. 

Native to the Indo-Pacific reefs and rocky crevices, this species arrived in Tobago and Trinidad in late 2010, and has now found its way to warm ocean habitats worldwide.

The thermal tolerance of these fish ranges from 10-300C. Moreover, they thrive in low-wave energy environments. 

Like other types of carnivorous fish that prey on other fish, the red lionfish’s behavior is influenced by ambient light. 

This means they are the most active during dusk and dawn, and like to rest and stay hidden during the daytime. 

However, a study suggests that red lionfish are becoming more diurnal feeders, enjoying their meals during the day.  

Red lionfish are prized among fishkeepers and aquarium trade experts, but people also use them as food in some parts of the world. 

  • Their Population is Growing Rapidly 

The distribution of red lionfish is growing at a rapid rate. 

This is seen as a concern in the United States, as some people think the increasing population of this non-indigenous species may pose dangers to the environment and to humans.

The primary reasons for the increase in the red lionfish population are that these species have no known predators, and their females reproduce all year long. 

A mature female is believed to release two million eggs a year, spawning every four days. 

External fertilization of up to 15,000 mucus-encapsulated eggs happens at a time. After 36 hours, larvae emerge, which then take 2-3 days to become competent swimmers. 

It is also important to note that red lionfish live up to 16 years in the wild. They generally reach maturity a year after hatching.    

  • They Exhibit Unique Foraging Behaviors

Red lionfish are known for using two foraging approaches: 

  1. They stalk the prey, sit, and wait for the right time to ambush. They chase the prey into a crevice to corner it, and then spread their pectoral fins to restrict its movement. 
  1. They spew water toward the prey to cause distraction when approaching it. This is known as blowing behavior.

Red lionfish tend to swallow their prey whole. 

  • They Eat Ecologically Important Fish

Red lionfish are a notoriously aggressive and invasive species. They gobble down species in native reef fish communities at an alarming rate. 

In addition to eating ecologically important fish, red lionfish feed on commercial species that people like to devour on dinner tables.

This is why humans started consuming these fish, to help curb their spread and promote the recovery of native fish species. 

It is also believed that red lionfish prey on rare species that have not yet been discovered. 

  • They Mainly Feed on Fish and Crustaceans

Adult red lionfish are believed to prey on fish (78%) and crustaceans (14%)

Many native organisms that these voracious predators feed upon have become endangered because they do not possess the ability to adapt and develop defensive mechanisms. 

One study demonstrated that 35+ fish species and 15+ crustaceans were found in the stomachs of lionfish in the Atlantic. 

These predatory fish can consume 8.2 times their body weight per year (on average) and fast for up to 12 weeks.    

The top fish species preyed upon by red lionfish include Grammatidae, Blenniidae, Gobiidae, Monacanthidae, Labridae, Atherinidae, Pomacentridae, Mullidae, Apogonidae, and Serranidae. 

It is believed that younger red lionfish feed on crustaceans, but as they grow older, their fish intake increases. 

Frequently Asked Questions 

Q.1 Are Red Lionfish Reef-Safe?

No. Red lionfish are usually described as being mischievous in reef tanks because they wreak havoc by eating everything in sight. 

They are also highly territorial and aggressive when living with other fish (including other red lionfish). 

You can expect fighting among the species if you keep red lionfish in a reef tank.

Q.2 Do Red Lionfish Have Teeth?

Yes. Red lionfish have rings of teeth that line their mouth. 

These rings contain around 70 tooth plates rotating like a conveyor belt to let new teeth come to the front. 

The red lionfish teeth are combined to form a beak-like structure. This allows them to crush the hard outer body of shelled species like crabs and urchins. 

Q.3 What is the Appropriate Tank Size for Red Lionfish?

You will need a minimum tank size of 100 gallons if you want your red lionfish to live comfortably. 

Also, make sure you install plenty of live rocks and crevices for them to swim along. 

Keep in mind that these species have an average size of 45 cm (length). This does not even include the tall fins and spikes on their sides and back, which can be an additional 20 cm.

The weight of red lionfish is also about 900 grams, reiterating that they need a spacious tank to thrive. 

The temperature of the water in the tank should be between 22-28°C. Additionally, a salinity of 30 ppm is considered ideal for red lionfish.   

Q.4 What Species Are the Best Tankmates for Red Lionfish? 

Since red lionfish can be extremely aggressive and territorial when made to live with other species, you must choose their tankmates carefully.

The venomous dorsal spines of these species can inflict a painful sting on other fish if they feel threatened. Moreover, they will eat just about any fish that’s smaller in size.

They also love to prey on shrimps, crabs, and ornamental snails. 

Hence, the only species you can safely keep with red lionfish are those that can defend themselves and stand up to the bullying behavior of red lionfish. 

Examples include larger angels, triggerfish, and eels. 

Never keep lionfish in a tank with other red lionfish, because they will fight until either of them dies. 

Q.5 What Should You Feed a Red Lionfish?

It is best to feed a variety of meaty food to your red lionfish. This could include shrimp, squid, herring, scallops, fish filet, and krill pieces. 

Just make sure the food is not cured with chemicals, or previously frozen. 

Summing It Up

In conclusion, red lionfish is an invasive species popular among fishkeepers around the world. They have a large pelvic spine, with multiple spines on the dorsal and anal sides. 

The body is covered with bright red and white stripes and spiky fins. 

These species are territorial and predatory, with no natural predators of their own. They enjoy feeding on other fish and crustaceans. 

When kept in a tank, red lionfish should always be fed meaty food and kept with larger species. 

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