How to Keep Koi Healthy

Keeping Koi healthy can be difficult for newcomers to the hobby. It is easy to get confused with so much information available. One of the major problems i encountered when I first became interested in the hobby was people giving advice about koi who’s knowledge was based around their experience in keeping a garden pond, a koi pond is quite different as koi grow much bigger than goldfish for example.

This article is not intended as a complete guide to keeping koi, but rather some points to consider and research further.

Koi Pond Water Quality

Water quality is key to the well being of koi carp. Koi like their environment to be stable, fluctuations in temperature and PH swings will weaken a koi’s immune system making them prone to infection and disease.

The key elements to good water quality and koi health are;

A large enough pond which is not over stocked
Adequate filtration system
Well designed pond with good circulation and no dead spots where harmful bacteria can linger
Plenty of Oxygen
Regular pond maintenance regime
Koi Pond Size

Koi are potentially quite large fish, a healthy koi should grow to around 2-3 feet in length. The bigger and deeper the pond the better but as a minimum you should not think about putting koi in a pond which is not at least 1500 gallons with an average depth of around 4 feet. The water depth is quite important as a shallow pond will be more likely to have sudden temperature changes, particularly in spring and autumn which are times of the year when koi often suffer poor health. If you can,t build a suitable pond of this size you should consider goldfish or some other common pond fish which would be happy in a much smaller environment. Overstocking a koi pond is a common problem, a pond this size could potentially stock around 5 or 6 koi. Any more than this and no matter how good your pond filter, you are likely to suffer continued health problems with your fish, in particular parasite infestations.

Koi Pond Filtration

A suitable koi pond filtration system should be installed. Do some research before purchasing your filtration unit as many pond filters sold are not designed for koi. The amount of food and resulting waste matter produced means a filter designed for a typical garden pond will not be able to cope.

A filter designed for a koi pond will usually have some kind of settlement area for solid waste to be removed prior to entering the biological filtration area. Usually you would circulate the pond water through the filter around every 2 hours, so your choice of pond pump must be considered. Water flowing too fast will result in poor water quality.

Well Designed Koi Pond

A well designed koi pond will have no sharp edges where koi could damage themselves and good circulation of water. Consider which area of the pond you are pumping the water from and where the water return is, for instance you don’t want your pump directly below your water fall!

A pond which feeds the filters via gravity is usually preferential to a pump fed system. Although more difficult to construct the final results are much superior and the pond will be much easier to maintain.

Koi ponds generally have very little plant life, koi will eat and dig up most pond plants creating a mess within the environment.

Good Oxygen Levels

Plenty of oxygen is required, usually a good waterfall will produce enough but air pumps are widely available.

Pond Maintenance

Your filters will need to be cleaned on a regular basis, I clean mine weekly during the summer months. This is a key consideration when choosing your pond filter as some filters can be more difficult than others to clean. Excess food, dead leaves, sludge and any other unwanted items should be removed from the pond on a regular basis.