Check the bill first: a swordfish has a broad, flattened upper bill, while a marlin’s bill is round in cross-section and spear-shaped. Then confirm the impression with body shape and dorsal fins. Swordfish are stout and rounded, with a tall crescent-shaped first dorsal fin and a much smaller second dorsal fin. “Marlin” covers several species, so fin profiles and markings vary; use color or size only as supporting clues.
The bill is the fastest reliable clue
In a clear side view, examine the upper bill from the side and, if possible, from above or below. Swordfish bills are wide and flattened, giving the blade a sword-like profile. NOAA Fisheries describes Xiphias gladius as having “long, flattened bills,” and its Atlantic identification key begins with the same practical distinction: “Upper bill flat; Single caudal keel → Swordfish.” See the NOAA Atlantic Swordfish and Billfish Identification Guide (resource page updated July 31, 2025; chart dated April 2019).
As an Amazon Associate I earn from qualifying purchases.
A marlin’s bill is narrower and rounded rather than blade-flat. It tapers to a spear point, so its cross-section stays more cylindrical as it extends forward. A photograph that shows only the bill can therefore be useful, but a foreshortened angle can hide the difference. Treat a frontal or highly oblique view as provisional and look for the fins and body before naming the fish.
What’s actually slowing this PC down?
Pick the symptom - the matching free tool is one click away.
Side-by-side comparison
| Feature | Swordfish | Marlin |
|---|---|---|
| Upper bill | Broad and flattened, blade-like | Round in cross-section, narrow and spear-like |
| Body build | Stout, deep and rounded | Generally more elongated; exact proportions depend on species |
| First dorsal fin | Tall and crescent-shaped | Profile differs by species; blue marlin has a pronounced dorsal fin, while striped marlin has a tall dorsal fin |
| Second dorsal fin | Much smaller than the first | Do not assume a swordfish-like two-fin contrast; inspect the species’ full dorsal profile |
| Tail | Broad, crescent-shaped tail; Atlantic key also uses caudal-keel characters | Tail and keel details vary among marlin species |
| Eyes, scales and teeth | Large eyes; adults lack scales and teeth | Species profiles differ; striped marlin are described with small teeth |
| Color and markings | Color is not a dependable stand-alone test | Blue marlin and striped marlin have different published color patterns; markings must be matched to the species |
| Typical maximum figures in NOAA profiles | Up to 14 feet and nearly 1,200 pounds; average fishery catch size 50–200 pounds | Pacific blue marlin: more than 12 feet and up to 2,000 pounds. Striped marlin: up to 12 feet and more than 450 pounds |
The size figures are potential or profile values, not a field rule. Their overlap is large enough that length or weight alone cannot identify a specimen.
#1 Best Overall
- [Ultra-Lightweight Ear Buds Designed for Small Ears] Each earbud weighs only 3.7g and features a compact, ergonomic in-ear design made especially for small ears. Secure, low-profile, and comfortable for workouts, all-day wear or overnight sleeping.The ultra-slim profile sits flush in your ear with no hard edges poking or rubbing, so you can even sleep on your side without discomfort.
- [Immersive Stereo Sound with TOZO OrigX Technology] TOZO OrigX tuning delivers clear vocals, balanced mids, and natural stereo sound for music, podcasts, and videos.
- [Long Battery Life for Daily Use] Get up to 7 hours of playtime on a single charge, with up to 32 hours total using the charging case—ideal for workdays, commuting, and extended listening sessions.
- [Bluetooth 5.3 & Stable Connection] Bluetooth 5.3 provides fast pairing, stable wireless performance, and reduced dropouts as you move around home or office.
- [Deep Bass with Clear Vocals] High-performance drivers produce punchy bass while keeping vocals clean and detailed for everyday listening.
What a swordfish should look like
Stout body and large eyes
A swordfish has a comparatively thick, rounded body rather than the long, streamlined outline many people associate with marlin. Its eyes are large. These traits are useful corroboration when the bill is visible but the dorsal fin is folded, damaged or partly hidden. NOAA identifies the species as Xiphias gladius in the family Xiphiidae; its profile is available from NOAA Fisheries’ North Pacific Swordfish page.
Two noticeably unequal dorsal fins
The first dorsal fin rises tall and forms a crescent-like curve. Farther back, the second dorsal fin is much smaller. That strong difference in height is one of the best body-level checks after the bill. In a side-on image, trace the top line from the head toward the tail rather than judging a single fin fragment: the tall first fin should be followed by a distinctly reduced second fin.
Tail and adult surface
The tail is broad and crescent-shaped. Adult swordfish lack scales and teeth, a useful biological distinction when a specimen is being handled or displayed and the mouth and skin can be examined closely. It is not a clue that can normally be used from a distant boat photograph.
Free tools Windows power users keep installed
One-click scans. No signup required.
Why “marlin” is not one single silhouette
Marlin is a common name covering multiple species in the family Istiophoridae. A blue marlin and a striped marlin can both have the characteristic round, spear-like bill yet differ in dorsal profile, body proportions and markings. Do not reject a marlin because it does not match a single textbook drawing.
Pacific blue marlin
NOAA’s Pacific blue marlin profile identifies Makaira nigricans. It describes a pronounced dorsal fin and a long, spear-shaped bill. The profile reports fish exceeding 12 feet and reaching up to 2,000 pounds; those are maximum figures for the species profile, not a normal observation or a diagnostic threshold. Read the full account at NOAA Fisheries’ Pacific Blue Marlin page.
Rank #2
- 【IP68 Waterproof Multifunctinal Smart Watch】Torjalph fitness activity tracker smart watch is IP68 waterproof technology ,you can wear it when swimming,handwashing,it's rain-proof which means that you perform multiple exercise modes outside without worrying about sweat or rain corroding your fitness smart watch,and this watch equipped with a 230 mAh large capacity battery magnetic charging ,and this sports activity tracker watch can be used 5-7 days If fully charged.
- 【Larger 1.83'' Full Screen Watch & Multi-dial Selection】1.83 inch full HD color touch screen smart watch for men / women provides excellent 240*284 resolution image quality ,This Bluetooth smart watch offers a better touch experience and remarkable immersion and ,more than 200 watch faces for you to choose from App"Da Fit ", you can change the dial style according to your mood to wear keeping the world on your wrist
- 【Accurate Activity Tracker Smart Watch 】sports watch activity tracker uses sweat and dust resistant breathable silicone strap, our Fitness Tracker Smart Watch for Android iOS Phones supports 12 sports modes,walking,running,bicycle,swimming,badminton,basketball,football,rope skipping. This bluetooth calls smart watch for men women is lightweight and stylish, bringing more convenient and relaxing sports experience while also providing more protection.
- 【Your 24 Hour Personal Daily Health Monitor】Fitness watch for women men full touch screen IP67 waterproof bluetooth smartwatch for Android iOS Phones with heart rate blood pressure monitor multifunction Andriod smart watch with steps counter sleep monitor sports fitness watch, monitoring blood oxygen saturation allows you to understand your physical condition in real time to track fitness progress ,to know your health status in time.
- 【More Functions Bluetooth Call Smart Watch】This fitness activity smart watch full screen for iPhone and Android phones includes a bunch of new features including:The bluetooth smart watch can hang up the phone, receive and display WhatsAPP /Text /Facebook /Twitter /Messenger reminder.Support sedentary reminder, alarm clock, stopwatch, timer,weather information,music control, remote camera control compatible with Android 5.0 and above or iOS 9.0 and above smartphones.
Striped marlin
Striped marlin (Kajikia audax) have a long, round bill, a tall dorsal fin, small teeth and blue stripes in NOAA’s description. Their reported maximum is up to 12 feet and more than 450 pounds. The stripes can support an identification when they are clearly visible, but an image with glare, blood, fading or motion blur should be judged by the bill and fin anatomy first. NOAA’s species profile is at NOAA Fisheries’ Striped Marlin page.
Do not transfer one marlin species’ traits to all marlin
A pronounced fin, blue stripes or a particular body outline belongs to the species description in which it appears. Use those details to separate likely blue marlin from likely striped marlin only after deciding that the fish is a marlin-type billfish. The family name explains why the bills are broadly similar; it does not make every marlin visually identical.
Quick wins for a faster PC:
Clear out junk files and repair common Windows errorsFree Scan →Scan for outdated or missing drivers - takes under a minuteDriver Scan →Repair Windows errors before they cause bigger problemsFix Now →Step-by-step identification from a photograph
- Locate the upper bill. Find the long projection from the upper jaw and determine whether the image shows its width. A flat, broad blade points to swordfish; a round, tapered spear points to marlin.
- Check the viewing angle. A side view shows length and taper, while a top or bottom view helps reveal whether the bill is broad and flattened. If the bill is hidden, cropped or viewed head-on, mark the result as uncertain rather than guessing.
- Trace the dorsal outline. Look for a tall, crescent-shaped first dorsal fin followed by a much smaller second fin, the swordfish pattern. A marlin has a more continuous-looking dorsal profile overall, but the exact fin shape must be matched to the species.
- Assess the body. A stout, rounded trunk and large eyes support swordfish. A more elongated body supports marlin, provided the bill agrees.
- Inspect the tail and rear fins. Swordfish show a broad crescent tail. In a detailed Atlantic specimen, the NOAA key also considers caudal keels and anal-fin characters; these are confirmation features, not substitutes for a missing bill.
- Use markings last. Clearly visible blue stripes can support striped marlin, but color changes with lighting, water, stress and image processing. Never let a color impression overrule a contradictory bill cross-section.
- Apply geography as context. Check whether the location fits the candidate species, but do not use habitat as the primary identification. Several billfish share tropical or subtropical waters.
- Consult a regional key when certainty matters. For an Atlantic specimen, follow the NOAA guide’s full decision path rather than stopping at a general internet illustration. Its measurements and fin characters can separate closely related billfishes.
How to read the fins without being fooled by a photo
Fin posture changes when a fish is swimming, jumping, lying on a deck or being photographed from above. A folded dorsal fin can make a swordfish appear less distinctive, while a raised marlin fin can look unusually tall. First identify where the fin begins and ends, then compare its height with the body depth and with the fin behind it.
For swordfish, the useful pattern is not simply “large fin”: it is a tall crescent-shaped first dorsal fin paired with a much smaller second dorsal fin. For marlin, inspect the entire front-to-back dorsal line and identify the species if possible. Striped marlin are specifically described with a tall dorsal fin; Pacific blue marlin with a pronounced dorsal fin. Those descriptions overlap in everyday language, which is why the bill remains the deciding feature.
Tail shape can reinforce the result. A broad crescent tail supports swordfish, but a cropped tail, spray or a fish angled away from the camera can conceal the shape. In the Atlantic key, caudal-keel structure is part of a more technical confirmation process; it is not a feature to estimate from a blurry social-media image.
Rank #3
- [Low Noise High Fidelity] New bee guitar cord with 22AWG oxygen-free-copper center conductors provides enhanced signal transfer, the PVC insulation material and the high-density stranded copper double shield provide noise rejection for quiet operation
- [Ideal for Choice] New bee 1/4 straight and right angle metal connectors, ensures a secure connection in any instrument, pedal, or amp jack. L shape great fro on stage guitar stands
- [Wide Compatible] Suitable for mixer, power amplifier, microphone, effector, decoder, equalizer, electoronic organ, electric guitar, electric bass and other electronic equipments. Widely used in the installation of smart home, karaoke speaker, professional stage audio, etc
- [Easy Disassemble] Making incidental repairs quick and easy! Very nice, flexible cable
- [Dont Hesite to Order] 24 hours customer services and professional technology team are standing by
Color, stripes and skin: useful but secondary
Color is particularly unreliable across photographs. Water depth, flash, white balance, reflections and the fish’s condition can all change apparent tones. Blue stripes are a stated trait of striped marlin, so they can be helpful when crisp and repeated along the body. They cannot prove that every blue-toned billfish is striped marlin, and their absence in a dark or overexposed image cannot rule it out.
The Tool Desk
Outbyte PC Repair FREERepair Windows errors before they cause bigger problemsFix Now →Outbyte Driver Updater FREEScan for outdated or missing drivers - takes under a minuteDriver Scan →Likewise, a smooth-looking adult fish should not be assigned by skin texture alone. Adult swordfish lack scales and teeth, but those details require a close view. Keep the surface observation as supporting evidence and return to the bill and fin arrangement for the actual decision.
Size and habitat: context, not a shortcut
Why size fails as a single test
NOAA reports swordfish up to 14 feet and nearly 1,200 pounds, with an average fishery catch size of 50–200 pounds. Its Pacific blue marlin profile gives more than 12 feet and up to 2,000 pounds, while the striped marlin profile gives up to 12 feet and more than 450 pounds. These ranges overlap and describe different profile populations and maxima. A large fish is therefore not automatically a marlin, and a medium fish is not automatically a swordfish.
What location can and cannot tell you
Swordfish occur across tropical, temperate and sometimes cold waters in three oceans. NOAA says they generally occupy deeper, cooler water during the day and move vertically into shallower, warmer water at night. Pacific blue marlin are described in tropical and subtropical waters of the Atlantic, Indian and Pacific oceans; striped marlin are described in tropical and subtropical Pacific and Indian waters. These patterns can make one candidate more plausible in a particular report, but they do not replace anatomy.
When the location is known, record the ocean, coast and approximate latitude, then compare that context with a regional identification key. When the location is unknown—as with an unlabeled market photograph—ignore habitat assumptions and rely on visible structure.
Rank #4
- Digital Family Calendar: BSIMB digital calendar wall touch screen puts an end to your chaotic life. Designed for busy families, the digital calendar keeps you organised and in step with your family. Assign different colours and tasks to each family member to make family scheduling easier and more intuitive.
- Easy Setup and Auto-Sync: Plug in, connect to WLAN and auto-syn your electric calendar in minutes. Digital wall calendar compatible with Google calendar, iCloud calendar, Outlook calendar, Cozi calendar and Yahoo calendar. Add events directly on the device or through the ecalendar app. Electronic calendar stays current whether you're at work or traveling—no manual updates needed.
- All-In-One Home Assistant: Smart calendar builds habits and encourage independence with personalised chores. Display daily meal plan to reduce the daily ‘What's for dinner?’ stress. To-do lists keep track of everything you want. Turning chores into valuable achievements with stars and rewards, making life easier and more enjoyable.
- Manage Anytime Anywhere: BSIMB electronic calendar for family stay connected with the powerful ecalendar app. Access and manage your digital wall calendar anytime, anywhere with free features like stars & rewards, photo screensaver, chore charts, meals plans, to-do lists etc. Electronic planner paid features like Magic Import tailor advanced tools for users with special needs.
- Stay in Touch with Loved Ones: Share photos or videos from your phone to electronic wall calendar with app, instantly update your life moment, and keep in touch with your family, especially those who are far away; you can also surprise your smart calendar digital wall by sending him a wish card; it's also great for keeping tech-illiterate elders in touch with the youngsters.
Using the NOAA Atlantic key correctly
The downloadable NOAA chart is expressly an Atlantic swordfish and billfish guide. It includes more than the broad swordfish-versus-marlin distinction: caudal keels, dorsal- and anal-fin shapes, and measurements around the anus and anal fin can appear in the decision path. That level of detail is valuable for a retained specimen or a sharp scientific photograph.
The chart is dated April 2019, although the NOAA resource page was updated July 31, 2025. Its anatomical pathway remains a useful reference; any fishing seasons, size limits or other regulations printed with an older chart should be checked against current local rules. Identification and management are separate questions.
Common identification mistakes
Calling every pointed bill a swordfish
Both groups have long bills. The relevant question is whether the bill is flattened and broad or round and spear-like. Length alone has little value.
Using a single silhouette for all marlin
Blue and striped marlin differ in published profiles. A drawing that fits one species may make another look “wrong,” even when the bill and regional context agree.
Do these 3 things before closing this tab:
1Scan for outdated or missing drivers - takes under a minute2Repair Windows errors before they cause bigger problems3Fix the driver behind crashes, sound loss and screen glitchesDeciding from color
Color can support a striped-marlin identification when blue bands are unmistakable, but lighting and water conditions can erase or invent apparent bands. Anatomy outranks hue.
Deciding from size
The reported maximum sizes overlap, and fishery catch averages are not species cutoffs. Estimate size only after the structural identification.
Trusting a cropped bill or fin
If the image omits the bill tip, the first dorsal fin or the tail, say that the identification is limited. A careful “likely” label is more accurate than a confident species name based on one hidden feature.
Quick decision checklist
- Flat and broad upper bill: identify as swordfish candidate.
- Round, spear-like upper bill: identify as marlin candidate.
- Tall crescent first dorsal plus much smaller second dorsal: supports swordfish.
- Pronounced or tall dorsal profile with an elongated body: supports marlin, then compare the likely species.
- Blue stripes: supporting evidence for striped marlin only when clearly visible.
- Large size or a particular ocean: context, never the deciding trait.
- Unclear bill or missing fins: consult a regional key and report the identification as uncertain.
Taxonomy and conservation context
Swordfish are Xiphias gladius in the family Xiphiidae. Pacific blue marlin are Makaira nigricans and striped marlin are Kajikia audax, both in Istiophoridae. These names help you choose the right species profile, but taxonomy does not remove the need to inspect the specimen’s anatomy.
Management status is not an identification clue. NOAA’s 2023 assessment found the Western and Central North Pacific swordfish stock not overfished and not subject to overfishing; a 2014 assessment found the Eastern Pacific stock not overfished but subject to overfishing. Those findings concern particular stocks and years, not what an individual fish looks like.
Bottom line for an uncertain image
Start with the upper bill, verify with the dorsal-fin and body profile, and only then use markings, size and location. A flat, broad bill with a stout body and strongly unequal dorsal fins points to swordfish. A round, spear-like bill points to marlin, but the final description should name the likely marlin species whenever the evidence allows. If the bill profile is not visible, use a regional key and keep the identification qualified rather than forcing a choice.
Quick Recap
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
