Koi Fish Digestive System & Changes in India - Growing Jumbo Koi and Colour(Color)

Koi have a monstrous appetite and an amazing sense of sight and smell to aid it . Remember how easily they swim up to you ,the moment you are there especially with food  and who can help but smile at the feeding frenzy . They should grow into Jumbo, just  by the volume they eat !
The Koi Digestive System (Metabolism)

As is obvious from the shape of the mouth, they are voracious bottom feeders- They quickly adapt to floating feed too, as we are all too familiar - But obviously struggle a bit more with floating than sinking feed; if you have noticed .
Now its might look strange that a Koi, which you have heard as being a omnivore, is actually a carnivore when its a fry - and a cannibal too .

Yes Kois do practice cannibalism when they are young !!!!

Well this has to do a lot with Darwinian laws- "survival of the fittest" and of course their digestive system - The digestive system of the Koi is also developing as the Koi is growing and they finally become omnivores - (just imagine you favorite fish being a cannibal or in most cases a possible victim -)( Its usually the Ogons that are cannibals as they grow faster as fry )

They actually never grow a stomach - So no acidity too - Lucky Koi ...Instead they have a long intestine .

As fry their intestines are only as long as the body i.e. food goes into the mouth and out it comes through the "A- Hole"..

So, minimal time for digestion. Hence they tend only process animal protein which is actually the best easily available and digestible source and not plants which take more time to process - simple  - So if your Koi manage to gobble up some of its smaller sibling whom it can manage to swallow- the faster it gets fatter ...

Now as it matures their intestines tend to get longer and typically twice their body length (sometimes reported as thrice) so they can majorly eat the plant matter too and any high protein than comes along the way .

Once the food enters the mouth, its crushed between the pharyngeal teeth at the back of the throat (on the bottom)  against a hard cartilaginous pad (on top) at the base of the skull.  

The food needs to be ground so that the digestive juices mix and can be absorbed by the fish -.You might have noticed during feeding that once they fill their mouth they tend to submerge and then re-emerge for more . Actually they are grinding it down ( their equivalent of chewing and swallowing) The pharyngeal "teeth" are continuously replaced as they wear out - New ones grow in the place of old one throughout their lifetime.

Now the ground food travels through the oesophagus , which is lined with cilia and goblet cells to easily allow the food to pass through the anterior intestines whole mucus-secreting cells that help lubricate the food and protect the intestinal wall ( which is lined with tiny finger-like projections that increase the surface area for greater absorption of the nutrients) from the harshness  of some of the material ingested .Still there is abrasion, the cells linings are replaced every few days because of damage by the food passing through.

Now the controversial point Peristalsis ,  a kind of a wave motion in the intestine  -which when stretched  Triggered by receptors at the entrance of the intestine to move the material along. This is debated whether it happens or does  the new food pushes the old food out - most people go by the "old replaces new" approach.Well we do know that they poop in about 5-6 Hrs especially if they have just eaten.

  Enzymes which are digestive juices are produced primarily by the pancreas, which is located as cellular islands within the liver and introduced into the gut thru a duct.  Other enzymes are produced in the lining of the intestine.  Also naturally occurring flora of bacteria in the gut help to digest and absorb the nutrients from the food. thats why prebiotics  and probiotics work better for Nishikigoi , Than for us humans. Some koi growers use probiotic yogurt (even though Milk protien  is not so great for koi )- they just mix it with the food pellets that they feed and this is highly beneficial especially when you see bad Koi poop floating around .


Now you can understand the possible negative impact of antibiotics in the feed on Koi. You can even use normal pro and prebiotic combination capsules - Open them up and mix with Koi feed - try to ensure that its hand fed (don't trow the pellets into the water )- Especially like from a feeding bottle -this ensures the probitic and prebiotic powder does not get dissolved in the water but instead enters the gut ...

This tells us why Indian Koi Carp (Well All varieties of carp) are gazers and are in constant search for food and are especially active in night - (I still don't know when they sleep ) so their metabolism is active for small quantities but constant sources of food makes them more happy and busy especially if they are searching in the roots - (We feed them periodic rich food generally,so i guess most of the time they are bored  and just poop out without digesting most of the nutrients )

Koi Carp (Nishikigoi) Digestive system and changes in India  

Now lets come to Nishkigoi in India- there starts the problem - Winter - We have no great winter time of 2 months especially in the South India - (North India does have Winters especially the Himalayan region of course )

In the so called winter months the temperature seldom drops below 15-Degrees Celsius  - especially in the coastal belt .So their metabolism never slows down - there begins the question . 

Now shouldn't they grow bigger -to monstrous size instead of Jumbo -- 

Well they just don't! ,nobody knows why but actually in nature, in the tropics like in India & Thailand fish do grow to huge sizes - eg: the Mahseer ,the Giant Siamese Carp & the Mekong Giant Cat fish - Indian Jumbo Koi Carp Just look like the colorful babies in front of these giants .So it might be that they just don't have the genetics .

But Koi Carp in India or any other Tropical region is kind of disadvantaged, because of no winter - Why - Simply the colour  - The subtle colour difference between an inflated and deflated balloon ( Deflated less bright - less pigment over  a large surface area )

The explanation is thus - when the metabolic rate reduces in winter fish uses the accumulated fat - it still has to continue with its other bodily functions doesn't it (Eg. breath , stay submerged- Maintain salt levels in the body  etc. ).So it shrinks in size a little and the colors intensify, and really latch on (deflated balloon) -once it starts feeding again in spring on more color enhancers and protein - the effect is much more visible .

More research is on the way for color enhancement in India but we are yet to produce a Champion - 

Well lets wait and see what time and peoples efforts have to offer  .

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