I think we probably are all aware of the fact that Koi originate from Carp who are from the Cyprinidae family. The Cyprinidae is the largest know family of fish and vertebrate animals known, there are upwards of 3,000 living and extinct recorded species!

Cyprinids are categorised as stomach less fish with toothless jaws, they therefore use gill rakers to effectively chew their food, so even carp can appear to be ‘chewing,’ though they are in fact grating food against specialised pharyngeal teeth.

1. Gills – Used for breathing. Fish use their gills to exchange gasses like carbon monoxide and oxygen. Gills are short threads of protein that are called filaments - they do all the transferring of ammonia into the water for instance. Gills are extremely efficient in extracting dissolved oxygen from the water within a pond, it is believed they can take 80% where as the average person can take 4%. This is done through a capillary network that provides a huge surface area, these are very thin and delicate.
2. Swim Bladder - Buoyancy control basically, it allows a fish to remain at a particular depth of water. Fish can remain neutrally buoyant without any real effort, just using their fins to move. Charles Darwin in his famous work Origin of Species reasoned that the air breathing vertebrates' lungs had derived from a more primitive swim bladder, this however is now thought to be incorrect and that the swim bladder derived from a more primitive lung!
3. Weberian Apparatus – This is an anatomical structure which connects the swim bladder to a fish’s auditory system, the connection allows for a much wider sound frequency.
4. Carp have no external ears like a human does, they rely on water being a very good conductor of sounds, this then bounces off a fish and travels through the fish into its ears.
5. Heart – Much like in a human the heart is for transferring blood, in a fish this goes to the gills first, after all they are one of the most important parts, making the transfer of oxygen in a fish highly efficient. After the gills the blood travels to the rest of the organs.
6. Brain – I don’t think fish are credited particularly for their intelligence, in brain mass compared to similar sized vertebrates they have only one fifteenth the size! What fish are good at though is storing sensory information on food, sound or smell. This is why often carp anglers who have captured a certain fish can struggle to catch it the same way again!
7. Liver – The liver is usually connected to the pancreas, which is used to break down food, and also any potentially harmful chemicals the fish may have come in to contact with.
8. ‘Stomach and Intestine’ – Closely connected to the liver, carp as touched upon before don’t have a stomach per se, it is usually a very long intestinal tract, where food passes straight through and is processed by chemicals.
9. Kidney- Carp have two kidneys that are in fact merged into one, fish need in relative terms a large kidney, its job is to regulate the excess of water that goes into a fish’s body as well as removing nitrogenous waste.
10. Spleen – Found in nearly all vertebrates this is technically a non-vital organ. It acts as a blood filter to red blood cells and is linked to the immune system.
11. Gall Bladder – Bright yellow or Green in colour the Gall Bladder produces bile to neutralise acid and help break down fatty foods.

So where did Carp Actually Come From?

Well carp are actually from the Black, Caspian and Aral seas of China and Asia. They can be traced back to over 2,000 years ago. There is a famous lyric from the late Han period in which the Lyric is a story of a man who is far far away from home who sends back two carp for his wife to cook. His wife upon opening the carp found a long silk strip with 2 notes “Eat well to keep fit” and “Missing you and forget me not”

Carp have long been a source of food across Asia and are still a modern day delicacy, they used to be a staple in Britain too! It is not a widely known fact that monks were the first modern fish farmers here, fish was a staple part of their diet on Fast days so this included lent and several other days throughout the year.