I thought I’d try something different today than the usual fish identification post.

Instead, we’re going to talk about telling the difference between two fish: the marlin and the swordfish. You’re not likely to run across either of these fish on a scuba trip, but they are commonplace on television (fishing shows, woohoo!) and on our dinner plates. For those that already know the difference, I congratulate you. The rest of us should read on.

First things first, both fish are members of the billfish family. Billfish encompass fish that have sword-like bills. This basically means marlins, swordfish, and sailfish.

Let’s get the easy one out of the way. A sailfish can be recognized by the large dorsal fin that looks like a sail that has accordion pleats. That’s the first test. If the top of the fish has a sail, it’s a sailfish. Done. For fun, let’s look at a picture. Oooh, pretty.

Marlins have a single dorsal fin that connects along the fish’s back to a short, soft-looking ridge. Swordfish, on the other hand, have a dorsal fin more like a shark, and even extends far up, looking somewhat like a feather.

Here is a picture of a marlin:

Compare that to this picture of a swordfish. Notice also that swordfish have pectoral fins that extend below its body, whereas a marlin’s pectoral fins are small and barely visible.

If you can’t get a good look at the fins, you may have to rely on body shape to tell the difference. Marlins have a long, tubular body that varies only a little in size along its length. A swordfish, while still elongated, has a more rounded body.

Check out the two pictures below. From what you’ve learned, which is a swordfish, and which is a marlin? Hover your mouse pointer over the image to see the answer.


Once you know a few differences, I think it’s easy to tell the difference between marlins and swordfish. Even if you get them confused with each other, I doubt anyone will think you’re stupid. As long as you don’t call one of them a sailfish.

On many reef dives, the beautiful queen angelfish may be so kind as to grace you with its presence. Fortunately, the protocol for visiting this royalty is fairly lax.

Physical description

Angelfish are unmistakeable, with the queen no exception. They have very flat, disc-shaped bodies, with blunt, rounded heads.

The dorsal and anal fins extend along the top and bottom of the body, trailing backwards like the fins on a sports car.

It is the coloring that sets the queen angelfish apart from its peasant brethren. In total, it is a combination of brilliant blues and yellows. Look for a dark ring on its forehead speckled with blue spots. This “crown”, along with the completely yellow tail, distinguish the queen angelfish from the blue angelfish.

The fish is mostly yellow with tints of blue. Blue also lines the queen’s fins, as well as blue on its gill covers. These colors are particularly noticeable because of their iridescent appearance.

Geography and habitat

Look for queen angelfish all through the Caribbean, from Bermuda down to Brazil.

They are found mostly on reefs, near the bottom. The queen angelfish will either be by itself or in pairs, although its mate is not a king angelfish, as you’d expect.

Further reading

Wikipedia
Florida Museum of Natural History
Aquatic Community

Photo by laszlo-photo

This interesting member of the wrasse (pronounced “rass”) family is a common sighting on many a dive trip.

Physical description

Shape-wise, the creole wrasse looks like a typical wrasse—elongated body, slightly forked caudal fin, and rear-trailing dorsal and anal fins.

The creole wrasse’s colors change through its life. Juveniles are almost entirely a deep purple to violet color.

As the fish ages, it develops a yellow patch on the rear lower part of its body. The tail fin also becomes a bluish or black color.

Their bright coloring makes them a difficult sight to miss.

Geography and habitat

Creole wrasse are common through the Caribbean, southern Florida, and even up towards Bermuda.

You’ll find them living on coral reefs, often in small schools.

Further reading

FishBase
Marine Species

Keeping up with a Finding Nemo theme, started last week with the regal blue tang, this week’s fish also makes an appearance in the Pixar movie. The character Gill (voiced by Willem Dafoe) is a moorish idol.

Physical description

Moorish idols are not big fish, reaching a maximum length of 23 cm (about 9 inches), but are often smaller.

Idols have a highly compressed (flat) body that is shaped like a disc. Sharply contrasted vertical bands of white, yellow, and black make them stand out.

Besides the color (which is shared by a few butterflyfish), the snout and dorsal fin are the defining characteristics of a moorish idol. The snout is shaped like a tube, with a tiny mouth on the end. The dorsal fin is long and extends backwards, narrowing into a trailing extension with a distinctive white color.

Geography and habitat

Moorish idols live in tropical to subtropical areas throughout the Pacific and Indo-Pacific regions. They are usually found in reefs, but are often spotted in lagoons as well.

They prefer flat reefs at practically all depths, and are not picky about clarity of water.

Imposters

If you are in the Caribbean and insist you saw a moorish idol, more than likely you saw an imposter. The two candidates are the pennant coralfish (sometimes called the “poor man’s moorish idol”) and the schooling bannerfish (also called “false moorish idol”).

If you need to distinguish between them, moorish idols have a completely black tail fin, with a thin white trim, while the others have yellow caudal fins. Also, the moorish idol’s tubular snout is distinctive. The others have narrow snouts, but aren’t nearly as elongated as the moorish idol.

Further reading

Wikipedia
FishBase
FreshMarine

Photo by laszlo-photo

The regal tang goes by several names, palette surgeonfish, royal blue tang, hippo tang, and blue surgeonfish. They are sometimes mistakenly called blue tang, which is a different type of fish, although they may be correctly called Pacific blue tang. I recommend sticking with regal tang.

Physical description

The regal tang has an ovular shaped body characteristic of its tang family. It can grow up to a foot in length (31 cm), making it a decent sized fish.

The regal tang’s colors set it apart in the family. It is a royal blue color with yellow fins. The yellow tail fin is bordered by black stripes on the top and bottom.

There is a black swirl on the top of the fish, giving it the appearance of a painter’s palette, resulting in one of its many names (palette surgeonfish).

Geography and habitat

The Indo-Pacific region is home to a variety of colorful creatures, and the regal tang is one more species to chalk up for these waters.

Look for these fish in coral reefs at all depths.

Trivia

Most people know that the title character from the 2003 Pixar film Finding Nemo is a clownfish, but what type of fish is his friend, Dory (voiced by Ellen DeGeneres)? That’s right, a regal tang. A bit of fun, spontaneous trivia for you.

Further reading

Wikipedia
Animal-World
FishLore

Photo by Jack Rydquist

I love goofy looking fish, and today’s fish identification definitely fits that description!

Physical description

We’ve seen triggerfish before when we covered the black triggerfish. The clown triggerfish has the same basic body shape. This means an oval shaped body that is very flat. Ventral fins on the body and rear dorsal fins “wave’ to allow slow movement through the water, giving triggerfish what is probably their most recognizable characteristic.

What distinguishes clown triggerfish is their coloring. The bottom half of the fish is covered in large white spots over a dark background. The top of the fish is medium sized black spots over yellow color. The fish also has a few white stripes, in particular below the eyes and along the dorsal, ventral, and caudal fins.

If all that color isn’t enough for you, clown triggerfish have distinctive yellow lips, large like their triggerfish brethren. These lips mask strong jaws used for crushing sea urchins and the like.

Geography and habitat

Sorry Caribbean divers, but the clown triggerfish is found in tropical Indo-Pacific waters. Even in this region, the fish is relatively rare.

Nevertheless, look for it at all depths around coral reefs.

Due to their colorful appearance, clown triggerfish are highly sought by the aquarium trade, despite being difficult to maintain.

Further reading

Wikipedia
Fresh Marine
Animal World

Photo by mjwinoz

Juvenile photo by cliff1066

The state marine fish of California, the Garibaldi damselfish (full name) is a common sighting off eastern Pacific waters.

Physical description

Garibaldis have the usual damselfish look: steep sloped head, heart shaped caudal fin, and the flowing dorsal and anal fins. However, the most identifying characteristic is their distinctive orange color. In fact, this bright red-orange color provides the fish with its name. It is named after Giuseppe Garibaldi, the Italian revolutionary famous for his red shirt.

Juvenile garibaldis are not as bright in color, and often have shiny blue spots which disappear with age.

Garibaldis grow up to 30 cm (12 inches) in length. Between their length and unmistakeable color, they should be easy to spot and identify.

Geography and habitat

As mentioned, garibaldi damselfish call the coastal waters off the western U.S. home. They are particularly common in San Diego, Los Angeles, and the islands of both these cities.

Garibaldi are fiercely protective of their home, particularly when eggs are present. They have even been known to nip at humans who approach too close to a deposit of eggs.

They are found at depths up to 100 feet in rocky areas, which they prefer to call home.

Legislature

Since it’s the state marine fish and all, California has taken measures to protect garibaldi damselfish. This link summarizes the legislation, but in short, you’re not allowed to kill or take garibaldi without a special permit.

Further reading

Wikipedia
Monterey Bay Aquarium

Photo by Stan Shebs

Juvenile photo by Randy Morse

Being a hogfish, the Spanish hogfish is part of the wrasse family.

Physical description

Spanish hogfish have the common appearance of most hogfish. Namely, the pointed snout that they use to root through the sea bottom. Spanish hogfish are 10-13 inches (25-33 cm) long, although fish who eat their Wheaties can definitely grow larger.

Spanish hogfish also have streamlined dorsal and anal fins which trail back. Along with the pointed tips of the caudal fin, this gives them an aerodynamic appearance.

Juvenile Spanish hogfish have an almost entirely yellow body, except for the upper front quarter, which is a purplish or possibly blue color. This is the Spanish hogfish’s most distinguishing characteristic. As they get older, the yellow fades into darker colors, like brown.

Geography and habitat

Despite their name, Spanish hogfish are not from Spain. The live in the warm Caribbean waters, only as far north as southern Florida and down to Brazil.

They live on the reef at depths as shallow as 3 meters down to 30 meters. They are constantly prowling for food. Look for them rooting on the sea bottom, or, if you’re fortunately, catch the juveniles cleaning other fish like snappers. Fish will open their mouths and gills, allowing the Spanish hogfish free access for cleaning.

Further reading

Wikipedia
FishBase

Juvenile photo by VenturaB.

Photo by brian.gratwicke