How to feed your koi pond fish.

Feeding time is arguably the most enjoyable koi keeping activity.

It brings koi and koi keeper together and reaffirms the relationship we have with our koi.

Depending on the size and stocking density of our pond, and the nature of our koi, feeding time can be a leisurely time as koi take their food gracefully, seemingly taking food with good table manners as it is offered by hand to them on a one-to-one basis. In more heavily stocked ponds, at the merest hint of food, the calm water can start to move with your koi’s frenzied anticipation, only to boil with a feeding explosion once the food hits the water.

Either way, feeding allows us to connect with our koi, and some have even suggested that koi sense the relationship and companionship they get as a part of the feeding experience.

Looking at feeding on a more practical level, feeding time is such an essential part of koi keeping because of our koi’s reliance on us for their food. Only we can ensure that our koi are getting sufficient food of the right quality. If they don’t get it from us, they won’t get it from anywhere else. Furthermore feeding time can act as a barometer for assessing the health of our koi. Those that don’t feed or are shyer than usual could well be showing the first signs of a health problem. Better test the water just in case.

Koi need and deserve a complete and balanced diet. This means that we must feed them a food that provides them with what they require in quantities that are balanced so that they don’t receive too much or too little of any one component. In the wild, koi would fulfil this need by foraging on an array of natural food items. In a koi pond, they look to us and the koi food we offer them to meet their need.

What forms does for koi food come in? Koi food is available in different formats, whether pellets (sinking or floating), sticks and paste. The same formulation can be offered in either format, with each form offering a number of benefits to us and our koi. However, there is little evidence that the format in which food is offered to koi has an effect on the performance of the formulation. So by choosing to buy a food in a different format is largely for our own benefit rather than the koi’s. (i.e. If you prefer the flexibility of being able to mix in your own ingredients into a diet, and hand feed your koi, then choose a paste food. (See Box Out)

It does exactly what it says on the tin.

Through the intricacies of food manufacturer, it is possible to make foods to perform different functions for koi.

Staple. Staple diets of the less glamorous of the koi foods that provide koi with a suitable balanced and complete diet that will maintain your fish’s condition. Consequently, they will prove to be more economical than other ‘high spec’ diets, but none the less, they will still provide koi with satisfactory nutrition.

Why choose a growth food?

We all love big koi. Whenever we view a pond of koi, it is usually the biggest koi (irrespective of its grade) that creates the biggest impression. We want our koi to grow as large as possible too, so that they reach their full potential and who knows may even increase in value too! To enable your koi to grow, they need to be given the means to grow, starting with a growth food.

How do they work?

A growth food is characterised by a high protein content. In order for koi to grow (assuming they have the correct environment of factors for growth) they must ingest more protein than they utilise for body maintenance. Protein is the only component of a diet that enables koi to build new tissue. The more protein, the greater the potential for new tissue growth (and bigger koi). A growth food is defined by its protein content, rather than its format, and high-protein diets are available in sinking or floating pellets, sticks and paste foods.

Things to look out for in a growth food.

You should look for a high protein (35% +) food that is formulated using high quality animal-based proteins such as fishmeal or poultry meal. These high quality sources of protein provide koi with all of the essential building blocks that a diet high in vegetable sources of protein may lack. In order to get value for money from the growth food, only use it when koi have the potential to grow (i.e. In water temperatures above 12 degrees C). Scrutinise the ingredient list to check which are the most abundant ingredients (they are listed in descending order). Lookout for foods were fishmeal appears higher up the list of ingredients. As with all koi foods, a growth food should be offered on a little and often basis throughout the day as this enhances a koi’s ability to digest its food, reducing pollution and improving growth rates. If growing koi as quickly as possible is your priority then you could easily consider installing an automatic feeder. In doing so you’ll be following the approach used in intensive aquaculture that has proved to be so effective. Simply measure out the day’s food (or longer) into the feeder and set it to feed at regular intervals. You don’t get the interaction at feeding time when you use an auto feeder, but your koi get the benefit of regular feeding throughout the day. Koi keepers that routinely use an autofeeder soon notice a decline in the koi’s association between the koi keeper and feeding time. A small price to pay for getting koi to grow rapidly, as long as you don’t miss the close interaction with your koi.

As mentioned earlier, your koi’s growth rates are governed by other factors besides food hence the varying size of fish in a pond. The most influential factor that causes your koi to grow at different rates in your pond is their individual genetic make-up. Some koi will show a greater potential for growth because they are able to utilise the food more effectively than other koi when held under the same conditions. There is a very close relationship between the complexity of a koi’s pattern and its growth rate, with less patterned koi (eg Chagoi) achieving faster growth rates and larger ultimate sizes compared to the more complex Go Sanke varieties.

How do I know if I have over fed my koi?

It can be tempting to offer koi as much food as they will readily consume when trying to grow koi as quickly as possible. But when feeding koi we need to appreciate that not only are we feeding our koi, but our pond also. It is more likely that when going for growth, you over feed your pond rather than your koi. When koi consume considerable quantities of food, their ability to digest and utilise it will decrease, leading to greater levels of pollution. So even if your koi don’t show immediate signs of being overfed, the water quality will soon start to deteriorate as the filter starts to struggle to keep on top of the ammonia workload. This in turn will cause your koi to show a change in behaviour, a loss of appetite, and if left untreated, the first signs of ill-health and disease. These symptoms are typical of a pond being overfed and will lag perhaps as long as one week behind the actual act of overfeeding. A period of intense feeding should be accompanied by vigorous and continuous aeration (preferably diffused and from the pond bottom) coupled with regular water testing for ammonia and nitrite.

There is a cost to the benefits of using a growth food, in that a pond that is subjected to the excessive or prolonged use of a growth food is likely to need more frequent water changes. The more protein that is added to an enclosed system such as a koi pond the more organic material the filter system will have to handle. When using such a rich food, pond water is more likely to discolour and the water may even start to froth or bubble due to the accumulation of dissolved organic substances.

Colour enhancing diets: In the same way that protein levels are increased for a growth food, a colour enhancing diet is formulated to include ingredients that enhance the colour of our koi.

Koi gain their pattern courtesy of the arrangement and different types of colour cells in their skin. These colour-forming chromatophores can be thought of as minute store houses for the pigment that they display. So areas of redskin are created by a localised and intense distribution of chromatophores that store red pigment. Colour enhancing foods contain an array of colour enhancing ingredients that are high in similar pigments (called carotenoids). In their wild or natural diet, koi would gain these carotenoids from natural sources such as algae, freshwater crustacea or invertebrates. As these are lacking in a koi pond, we supplement their artificial diets with similar algae, crustacea, or synthetic colour enhancing ingredients that will stop our koi from fading. Many of these colour-enhancing ingredients are only required in very small doses to keep their chromatophores ‘topped up’ with colour. It’s a good job because spirulina costs several thousand pounds per tonne!

Colour enhancing ingredients to look out for. These are only required in small amounts and will be found towards the end of the ingredient list on a jar of koi food. You should be looking for ingredients such as spirulina, marigold, paprika, krill as well as other synthetic (man-made) sources such as astaxanthin and canthaxanthin.

For the same reasons that koi will grow at different rates even when offered the same diet, similar genetic factors lie behind variations in koi colour. Colour enhancers can only enhance the potential a koi has for colour and cannot turn a low-grade orange and white Kohaku into a higher grade blood red fish if its genetic make-up doesn’t allow it. But where colours have faded on a previously intensely coloured koi, careful feeding with a colour enhancing diet can soon restore them to their former glory.

Skin quality is also affected by the whole environment, the background stress levels, and the mineral loading of the pond water. Black and white areas of skin are at their purest and cleanest in hard, alkaline waters and can fade through stress or excessive mucus secretion.

What are immune boosting foods?

Immune boosting foods are more than simply complete and balanced diets, and take their fish’s nutrition further by incorporating ingredients that specifically target and boost a koi’s immune system. In the same way that additives such as spirulina boost colour, there are also natural compounds that can be put into a diet to boost specific disease fighting processes. Beta Glucans: these complex sugars are derived from yeasts and are shown to increase the white blood cell activity in fish, reducing the threat of infection from bacteria and viruses. Mannan Oligosaccharides: these complex sugars are also derived from yeasts and have been shown to prevent specific disease-causing bacteria from attaching to host tissue, thereby preventing the initiation of infection.

Variety is the spice of life. Koi can become quite choosy if they are only offered one type of food, so it might be a good idea to mix a number of different foods for the desired effects you want. This also allows you to wean koi on to new foods when autumn approaches. Just as the temperature changes gradually over several weeks towards autumn, so too should their diet, weaning koi on to a lower protein food. At these cooler temperatures your koi will not grow and only require a lower protein diet that is sufficient to replace and renew old tissue. A higher protein diet would simply prove to be excessive and cause fish to excrete more protein into the pond, leading to a deterioration in water quality. Koi will generally stop feeding in winter at around 8OC, but be guided by your own koi as to when you should stop offering them food. Likewise, when tempting koi to feed for the first time in spring, use 8OC as a guide for when they are likely to feed.

Packaging. Just as your breakfast cereal deteriorate the longer it is kept open and unsealed, so too will your koi food. Air (in particular moisture) will accelerate the deterioration of food, encouraging moulds, fungi and other micro-organisms to indulge in your koi’s special diet. Look out for air tight, resealable packaging that allows you to keep moisture at bay indefinitely. Your cornflakes may turn soggy after only a week or so. Imagine what could happen to your koi food over a longer period if it is not stored correctly.

Food freshness. Vitamins by their very nature are highly reactive compounds and will be the first components of a diet to deteriorate. A fish foods sell-by date is determined by the expected life of the vitamins in storage. Most diets offer an 18 month shelf-life, with those foods with longer left to run on the sell-by date more likely to offer your koi complete nutrition for longer once opened.

Treats for koi.

Opinions differ on whether koi should be offered wholefood treats. When considering how well-equipped koi are to handle hard to digest food, it makes sense to offer than items that will allow them to use their digestive equipment. A bit like giving a dog a bone. Treats offer koi more than their crude nutritional value for, as they will act as a much-needed and often missed source of roughage that many artificial diets may not offer. Such treats can include:

Snails – allows koi to use are their pharyngeal teeth. Mussels and prawns – tough cartilage and connective tissue is a nice challenge for koi. Sweet corn and peas – may reappear undigested, but they do provide koi with a source of roughage Brown bread – soon becomes soft and malleable and easy to digest. Lettuce – a rich source of vitamin C and a source of entertainment for koi.

What’s in a food? Each food must offer koi a complete and balanced diet, containing proteins, carbohydrates, oils, vitamins, minerals and other additives such as colour enhancers and immunostimulants. Look out for the following ingredients and see what their function is in the diet.

Fishmeal poultry meal wheat germ , maize gluten – Protein sources used for growth, tissue repair, sperm/eggs production and energy

Wheat, Bran, Rice, – Carbohydrate sources used as a source of energy

Fish Oil – Oil source used in cell membranes and for energy.

Ash – Minerals – used in the formation of all tissues including bone, and blood.

Vitamins – Used in bioprocesses and to promote overall health and healing.

Spirulina, Krill, Marigold – Carotenoids used to enhance colour.

Why might my koi stop feeding?

Poor water quality: High ammonia and nitrite levels cause a loss of appetite. Investigate the cause of the ammonia/nitrite, stop feeding and carry out a water change.

Shy Koi – reluctant to feed. Check early morning/late evening for any heron or cat activity.

Change of food. Koi can become accustomed to a diet and may not take well to a new diet. Persevere with the new food and the koi should soon take to it.

Sudden drop in temperature. A sudden drop in temperature will cause koi to lose their appetite. But also test the water just in case.

Disease outbreak. If koi are overridden with a disease (eg whitespot) they will start to sulk and ‘hang’ in the water. Confirm the disease either visually or via a mucus scrape and treat accordingly.

Different Food Types:

Which Food Type? The different types of koi food can be divided into 3 groups.

Floating pellets & Sticks

Sinking Pellets

Paste Foods

Each food type offers a number of benefits to both koi and keeper, and can be considered for a number of practical reasons.

1. Floating pellets & Sticks

Floating pellets (or expanded pellets) are produced through a process called extrusion. Food ingredients are milled into a fine flour and heated into a paste which is then forced through a set of holes which determine the pellet diameter. As the warm paste is pushed through the holes under great pressure, they expand and take on air, creating a honeycomb of microscopic voids within its structure which makes the pellets light enough to float. A series of knives then cut this expanded sausage of paste into pellets which are then divided into the pellets we feed our koi. Floating pond sticks are made in a similar way where the knife cuts less frequently, producing a long stick rather than a more compact pellet.

2. Sinking Pellets.

A sinking version of a floating pellet can be manufactured in a similar way by preventing the pellet from expanding and taking on air during extrusion. As the resultant pellet is denser than water, it will sink.

Sinking pellets offer koi the ability to feed off the pond bottom (if the pellets actually reach the pond bottom before being eaten). They are a departure from the traditional floating pellet and should be used with care as any uneaten food may go unnoticed. Sinking pellets also do not bring the beauty of koi to the surface or allow us to see whether all koi are feeding. However, a sinking diet can be offered as a first food in the spring to encourage any reluctant feeders to come out of their winter slumber.

3. Paste Foods

Paste foods are produced by intercepting the finely milled ingredients prior to them reaching the extruder. Paste foods must be mixed with water to form a firm dough ball that can be offered, a piece at a time, to koi. Paste too is a sinking diet which rapidly stimulates the interest of all the koi in a pond. As soon as a paste is mixed with water, water soluble ingredients leach out into the water, alerting the koi’s acute olfactory (smell) senses that there is food about. The benefits of paste foods is that they are soft and moist and create frenzied feeding activity. However, they require mixing (creating twice their dry weight once mixed) and can cause a little clouding during feeding time (but nothing an adequate filter cannot handle).

Kill blanketweed and string algae.