What To Do If My Koi Is Unwell?

How to Know if My Koi is unwell?

Koi will show changes in there behaviour such as erratic swimming, flashing or flicking, swimming upside down or motionless, abnormal feeding patterns or not feeding at all and isolating themselves from others all these things an indicate that your koi fish is sick.

Physical symptoms also show us our Koi are not well like red fins, cloudy or popped eyes and swollen abdomen can also be used to correctly diagnose koi fish diseases.

Understanding Your Koi’s Behaviour

The best way to catch signs of disease, stress or infection early is to become familiar with your koi’s behaviours. Observing your Koi’s behaviours can indicate a wind range of health issues. Getting to know your Koi will help you to recognise when things are not right in your pond.

You will need to firstly observe their behaviour without them noticing you. Koi will get to know you by sight and may make movements towards you if they see you. They become used to you approaching to feed them even a sluggish koi will move quickly if it is anticipating food. Keeping an eye on them from a distance will help you spot any fish that is having a troubles. A lot of Koi hobbyists invest in cameras they can then watch there Koi’s natural behaviour when ever they want .

Always look for any koi congregating by the water flow or inlet or surfacing now and than They may be isolating themselves away or seem sluggish in the way they are swimming. They may also be swimming erratically or rubbing themselves along the pons walls, flashing or even jumping out of the water all these can indicate parasites have spread.

You will also need to observe your koi when it’s feeding time. Paying careful attention to any new koi that you have recently added to your pond make sure they are mingling maybe they are not eating at all or seem to not be interested in feeding?

Loss of appetite or erratic feeding is present in almost cases of stress and illness and is a sure sign that you should investigate further.

Things to be looking for

1. Koi Fish Faeces/Waste

If you see floating faeces, this means the koi has undigested food or may be trapped air. Normal koi faeces should sink and dissolve in the water quickly. Sinking Koi faeces is a sign of a healthy digestive system and good nutrient absorption.

Check to see what your feed your Koi is a good source of nutrients and is a good quality food also make sure there are not any harmful debris in the pond that they may have ingested.

2. Pond Water Quality

Water quality is so important  for your koi’s health.

Always check your water parameters with a water test kit and resolve any problems you may have as quickly as possible and keep up with regular pond maintenance and water changes Please see our The Importance Of Water Parameters/Water Quality page this explains the importance.

When your koi seem stressed without an obvious reason  testing your water is the first place to start.

There should be as close to zero ammonia/nitrates in your pond as possible. Imbalances can escalate very quickly and have devastating effects.

3. Koi Physical Body Examination

If you have observed any unusual behaviour patterns with your koi you will need to physically examine the specific koi. out of the pond. This will require netting the koi and placing it in a Koi viewing bowl, You can diagnose a lot with the naked eye but will need  a small microscope, because most of the parasites that effect koi are microscopic you will be able to look at the slime coat and get a much clearer picture. A simple inexpensive one will work great, and they are incredibly helpful, quick, and accurate for diagnoses.

Externally, check if there is any opaque mucus on the body do they have two much mucus or not enough  can you see any leaches or worms.

Next, run your hands along the body. If it has lost its natural slimy, slim coat or mucus or maybe it has become dry or sandpapery feeling.

Unhealthy koi may have scales that have risen up from the body, like a pinecone and look for red congestion on the skin the gills or mouth and make note if there is any bleeding or open wounds.

Please take a look at our Koi Diagnosis and Treatment Guide for more detailed information on Koi Parasites, infection and diseases.

Changes in your koi’s appearance to be looking out for

Koi’s Eyes

Koi eyes can give you many clues about an illness. Are they popping out, or sunken in? Are they infected? If you see any koi with abnormalities.

Koi Abdomen

The abdomen may become swollen due to bloating. Also look for damage or redness around the gills or the mouth. A koi who can not breathe properly will deteriorate quickly  so catching issues around the gills and mouth early is always a good idea.

Koi Gills

Infected gills will often have white secretion or abnormal amounts of mucus on. This can also be grey or yellowish in colour. You may notice the base of the gills are white, or see white when they are open for respiration.  Healthy gills have a deep pink colour. Also keep your eye on gill movement Koi can move there gills excessively when they have parasites.

Koi Flashing or flicking, jumping out of the water 

Koi that have a parasite or the pond water parameters are not right often display different swimming behaviours then they normally would, They tend to flick and flash off the sides and bottom of the pond or even off the bottom drain if you have one, they can also jump completely out of the water which can lead to your fish actually jumping out of your pond.

Other Signs to look out for 

Poisonous Substance

There is also the possibility that a poisonous substance got into the pond quickly killing all koi. Is there any construction or renovation happening nearby? Heavy rains will carry chemicals from far away and affect your koi’s well being.

Adding Water

A very common mistake is that pond owners add ‘fresh water’ during a water change, forgetting that the chlorine in our public water supply can kill koi overnight. It unfortunately happens more than you might think, so be sure the water you add has been Dechlorinated. Take a look at our Removing Chlorine From Your Pond Water page to help you.

Not enough oxygen

Oxygen deficiency can also be a cause, always make sure your pond has adequate oxygen supply and remember your koi need more in the summer hotter days Please see our Air pump page for a more in-depth help.