Introduction To Koi Fish Care

It’s Almost All About Water Quality … Believe It or Not

Learn Before You Leap Into Koi Keeping! Maintaining Healthy Fish Is Your #1 Goal

Koi Fish in Pond

There is no way to keep koi healthy (or alive) for very long in sub-par conditions. But unfortunately, this is the way most of us first start out! Most people who get bitten with “koi fever” are backyard ponders, who normally have a pretty looking, but WAY TOO SMALL gallonage pond with lots of nice water plants, and then one day decide “Hey! Let’s add some fish”.

So, off the ponder goes to a local gardening center or aquarium store in search of fish. And quite possibly, the person finds that not only are there common type goldfish to choose from, but there are these interesting other fish called "Koi".

Wow … they are unique, and not too much more money … and before you know it, the enthusiastic new fish-owner comes home with a few (or too many) koi in a plastic bag, ready to add them to the backyard pond.

Nine-times-out-of-ten … (sadly) disaster strikes soon thereafter. The koi develop one problem or maybe lots of problems … or they just end up quickly dying, with no initial signs of distress. Egads! Nobody at the garden center or aquarium store told the backyard ponder that it was going to start off like this! Aren’t pond fish pretty darn hardy?

Really … as long as you give them water to swim in and food to eat … shouldn’t they be as happy as can be?

Koi Are Not As Hardy As Goldfish

#1 True Fact: Koi Carp Require Higher Water Quality Than Goldfish Do

Most Retailers Selling “Pond Fish” Don’t Know Anything About Koi Health In The First Place …

Uneducated sellers of koi abound. It is a shame, it is not fair to those of us spending our hard earned cash on koi fish, but it is still more the norm than the exception. This is why it is imperative that YOU educate yourself before you make your first koi purchase. If you’ve already lost fish … don’t feel too badly. You’re in a huge “club” of sorts. My wish is that this article, and all the others on my website will help to improve your koi knowledge base.

So all that being said … what do you need to learn?

There really are no big secrets that aren’t supposed to be told to the average koi keeper, which is most us who are involved in the hobby. Truthfully, it isn’t that the retailer who sold you the koi was honestly out to “get you” and sold you fish that were just waiting to die on their new owner … it normally always comes down to the fact that the store employees just aren’t trained properly in the special needs of koi.

Now, if you are expecting your pond fish to live longer than one season and you are like me, which means you treat your koi just like your other beloved pets … then that means it is your responsibility to educate yourself on proper “koi keeping” techniques. That’s all.

Like anything else in life, there are very few things we can just enter into blindly and be successful at. A little preliminary research and education will go a long, long way in helping make your koi fish keeping efforts happy, rewarding and stress-free.

Fact: 95% Of Koi Bought For Ponds In The USA Die Within One Year Because People Don’t Know How To House And Care For Them Properly

Let’s Learn From Other Koi Keeper’s Mistakes

What successful koi hobbyists really and truly do wish for beginners to learn are the basic fundamentals and truths about the hobby that just can’t be ignored. One "truth" that I will briefly mention is this … you cannot successfully keep koi on the “cheap”. Not if you desire healthy, robust, enjoyable pets. Pumps and filtration equipment need to be purchased and installed, as an example. Stagnant water that gets increasingly more polluted as time goes on is nothing but a toxic environment for koi (and even the more hardy goldfish).

However, I have some good news for the beginner! There is no reason for anyone to have to reinvent the wheel in regards to this hobby. You don’t have to stand there trying to figure out everything by yourself. The groundwork to success has been laid before us by many others who’ve made many terrible, costly and frustrating mistakes.

The basic “rules” for maintaining healthy koi are quite doable and really haven’t changed much over the years. And nowadays, these facts are readily available via the internet to those wanting to learn. Yes, advances and new inventions that can greatly improve the hobby do occur and believe me, these too are enthusiastically shared amongst koi keepers worldwide.

Quality Pond Water = Healthy Koi

Don’t Underestimate The Need For Proper Bio-Filtration

Are You a Happy “Koi Keeper” … Or a Frustrated “Fish Fixer”??

Let me restate the question above another way to make an important point: there are two different hobbies we can choose from, koi keeping or “fish fixing”. Ignore the need for proper aquatic facilities and ignore the very important need for excellent filtration equipment, well then, you’ll eventually find yourself as a frustrated fish fixer, rather than a happy koi owner.

I don’t know about you, but I think koi keeping sounds like a lot more fun as opposed to constantly tending to sick fish!

Alrighty … In A Nutshell Here Are The Most Basic Yet Important Not-To-Be-Ignored Healthy Koi Needs

A koi’s needs are basically quite simple. If you provide these five things, you will have far exceeded what 95% of garden ponders ever provide to their fish. Your koi will more than likely thrive, while theirs die, or struggle with problems of one sort or another all the time.

Side note: Please realize there are a number of other extremely important practices that should be adhered to for maximum koi health and vitality. This overview is attempting to convey the most rudimentary aspects of koi keeping for the beginner.

#1 Have as deep a pond as you can to keep down sudden temperature changes, with 4 feet deep being the optimal minimum.

#2 Have bottom drains and sloped pond bottoms so the pond cleans itself — such easy maintenence!

#3 Have a pump properly sized to the gallonage, “head” and necessary turn-over rate required to circulate the pond water through the filters and pond itself.

#4 Have some sort of prefilter to continually get the fish waste out of the water. Look for a prefilter that is very easy to maintain. Hopefully one where it only takes a pull of a valve to flush the wastes out, quickly and easily.

#5 Have a biofilter with clean media! (This is why you need a prefilter. The prefilter keeps the biofilter from getting clogged with rotting fish excrement and other pond waste.)

The purpose of the biofilter is to do ONE thing, and one thing ONLY … to cycle the ammonia excreted by the koi. It must have good bacteria in order to provide high quality, stable water. It’s not just show koi that deserve these conditions. All koi deserve these conditions! PERIOD!

We all have different objectives with our water garden or pond. To me, koi keeping is such a fascinating hobby. When I started over 7 years ago, I had a 75 gallon, very poorly filtrated water garden puddle. I knew nothing about the needs of koi. I just knew I wanted some.

Well, I received four as a gift. I killed two koi fish within 2 weeks, experienced ulcers in another that I did manage to save (that’s another article all by itself) and I had the other one die much later because it had an infection called "dropsy" when it was purchased. (This is also another good story for another article!)

I decided enough was enough and started to educate myself. I studied the science and ecology of water and ponds. I started to learn about koi medical care. I even attempted to gain a basic understand of the engineering involved in pond plumbing.

These are topics that you ought to try and get a moderate understanding of so you, too, can have a garden pond that will support happy, healthy koi as pets for a long, long time.

AKCA logo

Though most hobbyists will never go this far with their training, I am an AKCA Certified Koi Health Advisor.

Click here to learn more about Associated Koi Clubs of America KHA Program Details.

Teach Yourself About Water Quality

Click on these links for in-depth information pertaining to specific aspects of maintaining high quality garden pond water parameters:


  1. I have always wanted a KOI pond. However, I live in Indiana and was afraid of the long cold Winter months. I am now moving to South Florida and I’m afraid of the extreme heat.
    Do people have Koi fish in South Florida? If so, I want all the material I can have in order to have a successful and healthy pond for the Koi. Your information is most wanted and needed. Thank you.

  2. Claudia Brownlie says:

    Hi Pabs: Wanting to have a Koi pond is one thing. Doing it right is another! I commend you for wanting to do research BEFORE jumping in blindly to dig a hole in your backyard and put in pretty Koi!

    To answer your questions: Yes – people in warmer climates like S. Florida and in freezing wintertime climates like Indiana have pond fish and/or Koi ponds. BUT – I stress BUT – to do so a true Koi hobbyist should and will have the proper filtration equipment installed, preferably a bottom drain installed too (to efficiently and immediately keep pulling the fish excrement and other debris out of the water), the proper pond depth (at least 4 feet deep!), NO rocks in the bottom of their pond (rocks catch all the fish excrement and then it sits there and bacteria and such starts to breed that is not good for fish health), and many other things.

    A dedicated and caring Koi hobbyist will also learn about water quality and will monitor their pond’s water using (afforadable) test kits. A knowledgable hobbyist will NOT overcrowd their pond with fish – “technically” a true Koi hobbyist will allow AT LEAST 200-250 gallons of water per fish – even if the fish are small. Koi can grow up to around 20″ long or so … and will grow rather quickly if you have excellent water quality and are feeding them the proper food. Do NOT feed them catfish food (or other similar foods) — all that food will do is cause fat, unhealthy fish.

    I studied a lot before I stuck the shovel into the ground to start digging out my Koi pond. I spent a LOT of money on an effective filtration system. Yes, I had problems and such along the way as most beginning hobbyists have, but I didn’t have disasters as most people do who just think you can dig a big hole, put water into it, have a little rinky-dink filter that basically only causes the water to recirculate through minimal filter media, put too many fish in their pond, etc. etc. And then they wonder why in the not-too-distant future that their fish start getting ulcerated mouths, or holes in their sides, or are constantly gasping for air, or are floating dead!

    I can only say do a lot of reading up on true Koi keeping and don’t be too eager to dig your pond until you’ve figured out the right shape, the filtration you’ll need and where you’ll place it and how you’ll do all the plumbing for it etc.

    The best place to start is the AKCA – ASSOCIATED KOI CLUBS OF AMERICA: Join a Koi club in your state if there is one – as is usual with most hobbyist clubs, the members will be most supportive and helpful to you. I graduated from their Koi Health Advisor program, which if you are really dedicated to the hobby is the very best way to learn Koi health techniques and such that will benefit you greatly.

    If nothing else, become an avid reader of information shared on Koi forums – just do an online search for “koi forums” and you’ll see many results.

    I could go on and on, but you’re on the right track – do your research, reach out to other Koi enthusiasts. Good luck and if you do dive into this hobby, take it slow and steady and you will likely have quite an enjoyable if not sometimes challenging (for sure!!) time! 🙂

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