Do these 3 things before closing this tab:
1Fix the driver behind crashes, sound loss and screen glitches2Repair Windows errors before they cause bigger problems3Scan for outdated or missing drivers - takes under a minuteYes. Cod have veins, along with arteries, capillaries, and a heart. Their blood travels in a single loop: from the heart to the gills, onward to the body, and back to the heart through veins.
How blood circulates in a cod
Cod are bony fish, and their circulation follows the typical fish pattern. The heart pumps oxygen-poor blood toward the gills. After taking up oxygen there, blood flows to body tissues, where small vessels exchange oxygen and other substances; veins then carry it back toward the heart.
- Heart to gills: The two-chambered heart sends venous blood toward the gills through the ventral aorta.
- Gas exchange: Blood reaches fine vessels in the gills, where oxygen enters the blood and carbon dioxide leaves it.
- Gills to body: Oxygenated blood leaves the gills and travels through arteries, including the dorsal aorta, to body tissues.
- Return to the heart: After passing through tissue capillaries, blood collects into progressively larger veins and returns toward the heart.
The gills are therefore part of the circulation, not just a place where water passes over the fish. In the gill filaments, blood flows through capillaries in structures called lamellae. In cod-relevant pathways, blood reaches the gills through afferent branchial arteries, passes the lamellae for oxygen exchange, and leaves through efferent branchial arteries; branchial veins can also carry blood back toward the heart.
How cod veins differ from human veins
Cod and humans both have veins that return blood toward the heart, but their circulation is arranged differently. A fish has a single circuit: blood passes through the heart once on each complete trip around the body, and it reaches the gills before the body tissues. Humans have a double circuit, with blood passing through the heart twice per full trip—once between the heart and lungs, and once between the heart and body.
#1 Best Overall
- THE ULTIMATE TOOL FOR AVID FISHERMEN – This fishing logbook notebook will become one of your fishing trip essentials, helping you log your catches, record vital information, and preserve your favorite moments and memories.
- USE YOUR NOTES TO IMPROVE YOUR PERFORMANCE – The logbook has 60 entries to document the date, location, moon phase, weather, barometric pressure, wind direction, tackle used, and more, and analyze what worked and what didn’t to improve your skills.
- MARK THE FISHING SPOTS YOU VISIT ON THE MAP – The fishing journal includes the maps of the United States, Canada, United Kingdom, and Ireland and Northern Ireland to mark the spots that you visit.
- DURABLE HARDCOVER, A5 FORMAT, THICK PAPER – This log record book has a portable A5 format (5.8 by 8.3 inches), a PU-leather hardcover, thick 120gsm paper, 3 bookmarks, an elastic band, a pocket for loose notes, and a pen loop for your pen.
- 60-DAY MONEY-BACK GUARANTEE – We will exchange or refund your fishing accessories for men if you aren’t satisfied with your fishing gifts for men or fishing equipment. Reach out to us via message to refund fishing things for men and fishing stuff.
| Feature | Cod | Humans |
|---|---|---|
| Circuits | One main circuit: heart → gills → body → heart | Two circuits: heart → lungs → heart, then heart → body → heart |
| Main heart pump | Two consecutive chambers pump blood toward the gills | Four chambers separate the pulmonary and systemic circuits |
| Where blood takes up oxygen | At the gills | At the lungs |
| Vein function | Returns blood toward the heart after it has passed through body tissues | Returns blood toward the heart from the lungs or body, depending on the circuit |
Because cod hearts receive oxygen-poor blood, it can be tempting to assume they do not have veins. That is not the case: oxygen-poor blood returning to the heart is a normal part of a fish’s single-circuit system.
Is the dark line in a cod fillet a vein?
Not necessarily. A dark line in a fillet cannot be identified as a particular vein based on appearance alone. Blood remaining in fish tissue and the appearance of a fillet can be affected by processing and bleeding, so a visible line is not a universal visual marker for a named blood vessel.
Rank #2
- Florida Saltwater Fish Identification Book – A quick, easy way to identify the fish or sharks you might see or catch in Florida Atlantic waters. This waterproof fishing chart contains information on seasonal rules, regulations, limits, and more for legal fishing.
- 100% Waterproof and Tear-Resistant Guide – Far stronger and more durable than laminated fishing guides. This fishing booklet is plastic, bound with stainless steel staples, and stain free. Do not worry about wet or messy hands. Scuba Divers can use this underwater. Our booklet can withstand extreme weather conditions and saltwater environments.
- Detailed Rules, Vibrant Pictures – Ensure every fish you pull in the boat meets strict fishing guidelines. Easily reference more than 70 fish and shark photos with detailed information on each species you might reel in.
- Excellent Gift! Never Leave Home Without It – We’ve made Florida fishing, especially saltwater fishing, more enjoyable because you will know exactly what you are pulling in. Our fish book is 8.5" x 5.5" - small enough to fit in a tacklebox, backpack, or boat glovebox!
- 100% Made in the USA. Support the USA and small businesses.
What this means for cod
Atlantic cod (Gadus morhua) is a bony fish, so the general bony-fish circulation described here applies. The species’ other identifying traits, such as its lateral line, do not change the basic answer: cod have veins, and those veins help return blood toward the heart after it circulates through the body.
Quick Recap
Best Value
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.
