The Best Koi Food for Color, Growth and Immune Support 2021 (updated)
One of the most important aspects of koi keeping is selecting the very best koi food with the highest quality ingredients. If you’re a new fish keeper or pond owner, this isn’t always an easy decision due to the sheer amount of different products on the market. In this article, we’ll try to make the choice easier by explaining what to look out for, as well as recommend our personal favorite koi food picks!
Benefits of High Quality Koi Food
Providing your koi with the best possible food is an essential part of the fish keeping hobby. Unlike wild carp, ornamental koi that we keep in ponds have been in-bred over generations to produce the fantastic variety and beautiful colors that likely brought us into the hobby in the first place. Sadly, as a result of the breeding, the koi have developed weaker immune systems in comparison to wild carp, and now require better fish keeping all-round to fully thrive.
One of the most important things is selecting a high quality koi food which contains all the essential ingredients a koi needs. Feeding your koi a low quality fish food, or a food lacking in an essential ingredient, can lead to all sorts of problems as they grow and mature, such as dropsy or koi ich. Furthermore, there are foods that are unsafe for koi to eat and should be avoided.
By selecting a koi food with a balanced and high quality ingredient content, you can ensure your koi are stronger and happier. Some of the benefits of a high quality food are listed below:
Better Koi growthKoi need both protein and fats to grow and stay strong in adult life. A malnourished young koi will not be able to grow fully without a good source of both these ingredients. Likewise, an adult koi will suffer if their diet is lacking a good source of both. Proteins, in particular, should come from aquaculture sources, and should not be substituted for lower quality proteins, such as plant proteins. A koi needs an aquatic protein source to grow to it’s full potential, with common ingredients being fish meal or shrimp meal.
Stronger Color and PatternA balanced diet will allow your koi to have the best color and the strongest pattern possible. Even though the strongest factor in regards to color is most certainly genetics, high quality foods can also play a part. A weak and malnourished koi will appear dull in comparison to a strong and healthy fish. As well as this, certain koi foods may come with color enhancer ingredients which work with the sun to promote a stronger color pattern. These ingredients are not harmful to fish, but also not essential to a kois diet, so it’s up to you whether you feel they’re worth the investment when selecting a feed.
Stronger Immune SystemSince ornamental pond koi have weaker immune systems due to the amount of breeding, a feed with all the right ingredients is needed to keep the immune system firing! Most high quality feeds come with everything needed to support a kois immune functions, with some also including natural immune booster ingredients to help boost the system overall.
Koi Food Ingredients – What to look out for?
If you’re researching the best food for your koi, the first thing you’ll likely look at is the ingredients label – but what are you looking for exactly?
Below is a list of common, and less common, ingredients that make up the bulk of koi fish food products. We’ve explained each of the important ones and provided information on what to expect in the best koi food brands, so you don’t accidentally buy a low quality feed.
1) Source of Protein & Percentage
Koi are naturally omnivores, and in the wild will eat a range of animal and plant based protein sources for optimal health. When looking at the list of your koi food ingredients, you should take note of both the protein source and its percentage by crude mass. You want proteins that come from an aquaculture, such as fish meal, shrimp meal, anchovy, or herring meal. Some brands will use a range of different aquatic sources for their protein, and it’s important that the first and second ingredient on the label is the animal protein source.
Being listed as the first ingredient indicates the aquatic protein (i.e., fish meal) makes up the largest proportion of the feeds protein content, with other secondary sources complementing the main source. Animal protein is packed with essential amino acids which carp need for optimal growth, and this is not something they can get from plant based proteins!
As well as the source, the percentage of protein content is also important as it can drastically raise the price of the food, or be too low for optimal growth. We recommend a protein content percentage of 30-40% for the best possible diet. Any more protein than this and your koi will struggle to digest it in a single sitting and it will be wasted. The problem with high protein content feeds is they can be expensive, and there is no reason to pay more for higher protein when the protein isn’t even being used by your fish!
Excess protein will not harm your koi, however, and so as long as the protein amount is 30%+ and you’re happy with the price, it will still be a good buy.
2) Plant Proteins (i.e., wheat/soy)
Plant proteins are much cheaper for manufacturers to add to feeds than animal based protein, but it is normal for there to be both fish protein and plant protein present. If a fish food contains, for example, fish meal (1st ingredient) and wheat germ (2nd ingredient), this is not necessarily a low quality koi feed. The reason being is that the fish meal will provide the bulk of the protein, and the plant source will provide both secondary protein and energy. This combination satisfies both the protein and energy requirements for koi, with the plant content being used mainly for energy purposes (as well as some fats), and the animal protein will be used for growth, muscle development, and amino acids.
It should be noted that plant protein is totally devoid in essential amino acids which all fish require for tissue, organ, and growth development. Even if you select a feed with plant protein as a 1st ingredient, you should still ensure there is an aquatic animal protein source somewhere on the ingredient label to ensure your koi are getting a good amount of amino acids.
What you NEED to avoid is brands that have no animal based protein and just multiple plant based sources. This is cheaper for the manufacturer, but also much worse for your koi as they’re not getting the best protein source which is natural to their diet. Plant based protein as a primary source is much lower in quality and no substitute for an aquatic animal protein.
3) Fat Percentage
Another important food ingredient is the fish food’s fat content. The source of fat content is not as important as the protein source, with most labels simply using the term “crude fat” to refer to the content. In general, if your koi are small and still growing you should select a feed with a higher fat content. On the build up to winter having higher fat content in feeds can also be useful for packing on extra weight for hibernation/torpor. During warmer months, a lower fat content feed can be used to keep your fish trim, especially if you have mostly adult carp. As a guide:
- Young Koi: 3-12% Fat Content
- Adult Koi: 3-6% Fat Content
4) Vitamins, Minerals, & Immune Boosters
An often overlooked but very important ingredient in koi feeds is a good vitamin and mineral profile. Having a wide range of vitamins in a koi’s diet will help promote healthy skin, eyesight, digestion, growth, and even stronger color. One of the most important vitamins for koi is Vitamin C, or Ascorbic Acid. This vitamin will help a koi combat bacterial and viral infections and aid in the development of cartilage and collagen. When selecting a koi food, be sure to check for “ascorbic acid” or “vitamin C”, as it’s one of the best ways to boost your fish’s immune system naturally.
Alongside vitamin C, vitamins A, B, and K are all also important, contributing to to healthy scales, eye sight, metabolism, blood regulation, and tissue development. These secondary vitamins are usually obtained from the protein & fat content of the feed, but most feeds will display them individually so you know they’re present. If there are no vitamins being shown on the product label, that is a major red flag and may indicate extremely low quality ingredients or ingredients that have been hugely over processed, removing essential nutrients.
Another thing to consider is if the koi feed contains any immune system boosters, which can be both natural and synthetic. Most high quality koi foods will contain vitamin C as standard, which is an essential component to healthy immune activity. Other feeds, however, may brand their food as “immune boosting” and contain extra ingredients to further heighten the immune response. Common branded immune boosters include, Optimun, Aquagen, Torula Yeast, Bee Propolis, Lactoferrin, among others!
Although certainly not as essential as good quality proteins, fats, and vitamins, having an added immune boosting agent is always welcome within a feed, especially during times of added stress or infections (i.e., torpor period).
5) Natural & Synthetic Color Enhancers
Another ingredient that is not essential to a koi’s overall health, but is often desired as a koi owner if you want to enhance the color and patterns of your fish. Color enhancer ingredients can be both synthetic and natural, with synthetic options being cheaper and more potent, and natural options being less potent and sometimes more expensive.
The two most common natural enhancers include spirulina (blue-green algae) and shrimp/krill oil. Shrimp and krill oils provide almost as good color enhancement as many synthetic ingredients, but also tend to raise the overall price of the feed. Spirulina is a very common natural color enhancer, and is often included in almost all high quality feeds due to its cheap nature. You likely won’t see huge color differences with spirulina alone, but it works very well alongside other synthetic enhancers to maximum pigmentation.
In terms of synthetic enhancers, common one include Canthaxanthin and Astaxanthin. These type of color enhancers are much more potent in comparison to most natural ingredients, and are also fairly cheap for manufacturers to include, so they won’t have a huge effect on the overall price. Their safety profiles in ornamental fish are very good, with some studies even showing astaxanthin having other potential benefits outside color enhancement, including strengthening the immune system against harmful bacterial infections. Both are a very good choice for fish keepers wanting maximum color and vibrancy, and can be coupled with natural ingredients for even better results.
6) Crude Ash Content
A final ingredient that you have likely seen on other animal products is crude ash content. This is essentially a waste product that is left behind after the feed is processed, being made up from mostly carbon and mineral content. There will be some ash content in all feeds, but the lower the better! If you have two almost identical feeds, and one has a higher ash content, you should select the one with the lowest ash. Fish will obtain some of the mineral content from crude ash, but this is marginal, and most of the ash will simply be excreted by fish and build up as waste in the pond system.
Since listing ash content is not required by law in some countries, you will often find no accurate percentage for ash content on the feed. If you have an amount, great! If not, you will just need to review the rest of the ingredients and make an informed decision based on the quality of other content.
Koi Pellets Vs Koi Flakes – Does it Matter?
Although not as important as the ingredient content of the food, when selecting a koi feed you’ll also have a choice between pellets, flakes, and sticks. Although koi do in fact have teeth, they won’t be chewing their food in the typical sense, and will instead choose to swallow any food you provide whole – so you need to make sure they can actually eat what you give them!
For all types of koi foods, you should choose a food that floats easily and is not too dense or hard. It should also not break apart too quickly on the ponds surface, as it just needs to be softened enough for koi to swallow. Food that breaks apart too quickly will contribute to waste and rises in ammonia over time as the nutrients leak into the water.
Other that that, the choice between pellets, flakes, or sticks is really just a matter of preference. In general, for young/small koi, we would recommend flakes (or small-medium pellets) as they’re just easier for them to swallow. For larger koi you can choose between any pellets or sticks, but we tend to prefer pellets due to the shape making them easier to swallow. We also find that sticks tend to break apart quicker than pellets, whereas pellets are denser and stay on the surface longer.
There really isn’t a wrong decision here, and the choice of koi food should depend much more on the actual quality of ingredients. If a koi food is high quality, you can select any shape of feed and be successful!
The Best Koi Food Reviews 2021 (Full Ingredient Analysis)
Due to the different brands available between the US and UK markets, we’ve researched and divided our categories to provide both American and UK pond owners a review on the best koi food available. We have listed below the best food for koi available to both the US and UK market, including top color enhancing foods, immune boosting foods, and general all-season feeds!
US - Best Koi Foods
A highly balanced, affordable, and high protein koi food which works well as a feed in both warmer and colder months. The Hikari-Saki range are a medium sized pellet feed, which soften fairly quickly on the surface water but still hold their shape firmly. The pellet size at 0.2″ (5 mm) would be fine for both young koi and adult koi, and your fish should have no problems swallowing these tasty treats after softening.
The feed has a fantastic nutritional profile for its price; containing a wide range of vitamins, minerals and high quality protein source. The primary protein source is fish meal (1st ingredient), with added wheat germ meal as a secondary source of protein and healthy fatty acids. The total crude protein value by weight is a guaranteed 37% minimum, which is a respectable amount and exactly what we’d expect in a higher-end koi feed product.
In terms of fats, the feed has a minimum crude fat content percentage of 5%, so would work great as a leaner food option for fully matured adult fish. For growing koi or young fish, choosing a feed with slightly higher fat content may be more desirable, but you can always mix-in higher fat feeds (or treats) during feeding, or supplement with additional normal feedings to help pack on weight when needed.
The feed contains a wide vitamin profile, including vitamin A, D, E, and Vitamin C in the form of L-Ascorbyl-2- Polyphosphate. The good range of all the essential vitamins will ensure your fish maintain healthy digestion, strong immune systems, and better color & pattern. Alongside the wide vitamin profile, the feed also comes with a natural color enhancer to help with pattern vibrancy called Spirulina, as well as an immune booster called Brewers Yeast. Spirulina, which is essentially a form of algae, is a decent natural color enhancer but not quite as powerful as some synthetic choices, so we probably wouldn’t purchase this feed if maximum color enhancement is your sole priority.
The only issue we have with this feed is the slightly high ash (filler) content percentage of 15%, although since the rest of the ingredients are so high quality, it certainly isn’t a game breaker.
Overall, an affordable and balanced koi feed which would be suitable for both small and large koi, although a slightly higher fat content feed may be preferred for very young fish. A good choice for pond owners on a budget who still want high protein, vitamins, and the added benefit of color improvement!
- Type: Medium Pellets
- Season: All Season feed (Wheatgerm included)
- Protein: 37% (1. Fish meal, 3. Wheat germ)
- Fat: 5%
- Ash: 15%
- Vitamins: A, C, D E & Minerals
- Immune Booster: Yes – Brewer’s Yeast & Garlic
- Color Enhancer: Yes – Spirulina & krill
For maximum koi growth and development! Dainichi Koi’s Premium feed is packed with a huge amount of easily assimilated proteins from a high quality protein source – white fish meal. The feed contains 42% crude protein by weight, with the primary sources being from fish meal, then krill meal, and then soybean meal.
The feed also contains wheatgerm meal for added energy, extra protein and healthy fatty acids, but the wheat only contributes to a small percentage in comparison to the total fish and krill proteins.
The feed also helps improve the color of your koi, with both krill and spirulina proteins naturally enhancing the colors and patterns in carp. A wide vitamin profile is included, with vitamins A, B, C, D, and E for immune support and extra luster and coat shine. Brewer’s Yeast can also be found here, which is a great substance for promoting healthier digestion and good bacteria growth in the fishes gut.
Natural color enhancer spirulina can be found here, which works alongside the krill protein to bring out some extra color pigmentation in the scales. Although this combination isn’t the best color enhancer around, the feed is designed more so for digestion, immune support, and overall good health – the extra color should be considered a bonus here!
On top of this, we also have Calcium Montmorillonite Clay which is a famously used Japanese koi ingredient that helps natural digestion by neutralizing toxic particles and improving the intake of minerals from food. This is an interesting ingredient we don’t often seen in commercial feeds, so it’s great to see it included here! Alongside the wide vitamin profile, raw garlic helps fight back internal parasites, with the clay helping with absorption in the digestive tract for maximum results. A particularly good combination during cold weather months and during the build up to hibernation/torpor.
In terms of size, the pellets are around 5.5mm and float on the surface water. They’re a little harder than other feeds, but koi should have no issues with swallowing as they do soften in time. The super high protein from aquatic sources and the addition of clay, garlic and great vitamin profiles makes this feed one of the best for growth and development!
- Type: Medium Pellets
- Season: Summer feed
- Protein: 42% (1. Fish meal, 2. Wheat germ, 4. Krill Meal)
- Fat: 4%
- Ash: 9%
- Vitamins: A, B, C, D E & Minerals
- Immune Booster: Yes – Calcium Montmorillonite Clay & Brewers Yeast
- Color Enhancer: Yes- Spirulina & krill
Another popular food choice is Total Koi’s Sho Koi immune system boosting mix. This particular koi food is aimed at owners who want to help boost the immune system of their fish, as the feed contains a wide range of vitamins, minerals, and the exclusive immune booster “Optimun”. This substance has many potential benefits, with it being a rich source of nucleotides, a key component of a fish’s DNA and the immune system. The production of nucleotides is a time and energy consuming process, and supplementing with Optimun has been said to improve the development of cells associated with the immune response, which will help koi fight off bacterial and viral infections.
On top of this interesting immune boosting agent, the feed contains a high concentration of vitamin C, which also plays an important role in the immune system. Alongside we have other beneficial vitamins, A, B, D, and E, as well as trace minerals which help with various bodily functions.
Natural color enhancer spirulina is included, and although this isn’t the most effective color boosting ingredient available, it’s a nice bonus on top of the immune system enhancing properties.
In terms of nutrition, crude protein content is 38% by volume and comprised mainly of wheat germ and anchovy meal. Sadly, the anchovy protein is only second on the ingredient label, which means wheat germ makes up a high proportion of the protein content by total mass. Due to this, we recommend this feed mainly as a cold weather feed (where wheat germ is more useful), or as a supplemental feed to mix in with your regular feed for extra immune system support. It’s not a total deal breaker, as anchovy meal still makes up a large portion of the total protein and the rest of the ingredient are great, but it’s still something we’d like to report on.
An upside, however, is that this feed contains some of the lowest ash content of all feeds we investigated, coming in at just 4% of the total food volume. This low ash content makes it a very good choice if you want to optimize your water quality, or as a primary cold weather feed when filtration (bacteria) are less efficient at breaking down waste. Couple this with the great vitamin profile and added immune boosters and you have a really great cold weather food option for a safer winter period!
Overall, we like this feed for its great immune boosting properties, low ash content, and wide vitamin and mineral profile which aids in healthy bodily function. Recommended as a cold weather feed, or when mixed in with your primary feed to help boost the immune system of your koi.
- Type: Large Pellets (4 mm)
- Season: All Season Feed (Contains Wheatgerm)
- Protein: 38% (1. Wheat germ, 2. Anchovy meal)
- Fat: 6%
- Ash: 4%
- Vitamins: A, B, C, D E & Minerals
- Immune Booster: Yes – OPTIMÛN
- Color Enhancer: Yes – Spirulina
A koi feed for maximizing the color of your fish, while still providing plenty of nutrition, fats, and vitamins for optimal growth. Aqua Master’s Color boosting koi food range contains the synthetic color enhancer ‘astaxanthin’ and the natural color enhancer ‘spirulina’. When combined they form a powerful color enhancing combo, providing more vibrant pigmentation within as little of 30 days of constant feeding. This combination of color enhancers is one of our favourite, as it brings the benefits of both natural and synthetic agents, with astaxanthin potentially having further benefits outside color enhancement – such as strengthening the immune system against bacteria.
As well as the color enhancers, this feed contains a decent range of vitamins and minerals for optimal koi health. Vitamin C is present as L-Ascorbyl-2- Polyphosphate, and the feed contains plenty of fatty acids in the form of natural fish oils. Overall crude fat content is also fairly low, at 4% by volume, making it a great feed for adult fish or as a main warm weather feed where extra fat isn’t required. Vitamin A, D, and E are also present which will help with immune support and other essential bodily functions.
The crude protein content is 40% minimum, with the primary sources being fish meal, krill meal, and wheat germ. The first and second ingredient on the label is the aquatic animal protein, which means the bulk of the protein is coming from highly quality sources which will be packed with essential amino acids and energy. Krill is also a fantastic natural color enhancer, so will help complement the main color boosting ingredients to create an even more intense color.
There is no dedicated immune boosting agents in this feed apart from the essentials, such as vitamin C and high quality proteins/fats. The primary goal of this feed is maximum color enhancement, which it obtains with a great nutritional profile and some fairly potent color enhancer combinations.
The pellets soften fairly fast on the surface of the pond, so should be easy for koi to swallow. Pellets come in both small and large varieties, so should be suitable for both young and adult carp.
Overall, a great feed for optimizing koi color, as well as being high in quality proteins, healthy fats, and a range of essential vitamins and minerals. Our choice for the best color development!
- Type: Large/Small Pellets
- Season: Summer feed
- Protein: 40% (1. Fish meal, 2. Krill meal, 3. Wheat germ)
- Fat: 4%
- Ash: 12%
- Vitamins: A, C, D E & Minerals
- Immune Booster: No
- Color Enhancer: Yes- Spirulina & Astaxanthin
An all season koi food with a strong nutritional profile of vitamins and probiotic beneficial bacteria. The pellets have been designed for maximum uptake with as little waste as possible, and alongside the beneficial bacteria, they help your koi digest nutrients more optimally.
As well as the probiotic bacteria that aids digestion, this koi food also contains a natural and synthetic colour enhancer. Spirulina is a fairly good natural enhancer found in simple algae cells, and Astaxanthin is a synthetic enhancer which should provide a noticeable boost in colour over time.
The primary protein source is from both fish and krill meal, with a secondary being yeast wheatgerm for energy. The protein percentage is high, around 38%, with the fat content being around 8% in volume. Due to these fairly high values, this would be an ideal feed for growing koi, or koi that may need to put on some strength. The feed also contains a immune system booster called Stimune which has been shown to boost antibody levels and help fight back bacteria and viral infections.
The pellets are of medium size, around 6mm in width, so would be suitable for both young and adult koi. They’re fairly dense and soften gradually, allowing your koi time to swallow them.
Overall, a great all round feed with a quality range of ingredients. Would suit both small and adult koi, and will work to boost both immune system strength, growth, and color quality. Due to it’s natural and synthetic colour enhancers, you should see a strong colour improvement in your koi after a few weeks of feeding. For our guide to all of our recommended NT Labs Medikoi foods, click here.
- Type: Medium Pellets (6mm)
- Season: Summer feed
- Protein: 38% (1. Fish meal, 2. Krill meal, 3. Wheat germ)
- Fat: 8%
- Ash: 11%
- Vitamins: A, C, D, E, Minerals
- Immune Booster: Yes – Stimune
- Colour Enhancer: Yes – Astaxanthin & Spirulina
One of our personal favorite UK Koi feed brands is Evolution Aqua’s Premier feed range, though we have used and recommend all Evolution Aqua feeds. This koi feed contains no artificial colours, and a large vitamin and mineral profile, including Vitamin C and Omega 3 & 6. The feed supports both natural color enhancement, and comes with an immune booster which works alongside the feeds high digestibility.
Although not as strong as some synthetic colour enhancers, Spirulina, which is included here, still provides decent colour improvement and is easily absorbed by the koi. The feed contains its own immune system booster called BioMos, which is a strain of yeast designed to improve digestion and help with immune system support.
The protein content is primarily fish meal, wheat germ, and soya protein, and comes in at 37% crude volume. The feeds fat content is around 7%, and it has a low 7.5% ash content as standard. The feed is one of the most “balanced” koi foods we found, containing a good combination of protein, fats, and low ash content for better water quality. Although no ingredients really stand out as unique, this feed would be suitable for almost any purpose due to its finely balanced nutritional profile which contains a great mix of all kinds of ingredients for all seasons. It’s also very reasonably priced for how much food you get, which makes it a good choice for budget conscious fish keepers!
In terms of size, the pellets are medium sized and soften fairly quickly in water, so koi should have no problems swallowing them. They should be suitable for both young and adult fish, with the fairly high fat content helping younger koi pack on extra weight as they grow.
Overall, this is a great “all round” balanced feed for both natural colour enhancement, growth, and immune support. It would be suitable for both young and adult koi, or koi owners looking for a high protein, low ash, high quality koi feed at a reasonable price point.
- Type: Medium Pellets
- Season: Summer feed
- Protein: 37% (1. Fish meal, 2 Soya protien)
- Fat: 7%
- Ash: 7.50%
- Vitamins: A, C, D, E + Omega 3/6
- Immune Booster: Yes – BioMos
- Colour Enhancer: Yes – Spirulina