10 tips to keep your koi healthy

The important thing about koi fish is that they are of the carp family, and looking at them closely, you will notice the familiar whiskers on the sides of their mouths. Koi fish live better in a pond that has adequate filtration and water movement, because a koi needs to have at least 1,000ℓ of water to remain healthy, and keep in mind that they can grow to over 90cm.

The Japanese have a saying: “Learn how to keep water, then you have fish” – as each pond has its own ecosystem and a balance is required.

  1. Water quality

When topping up water in the pond, only add 10% normal tap water at a time, because municipal water contains chlorine that can kill your fish, and borehole water does not contain oxygen.

2. Ideal quantity food

Do not overfeed your fish, as leftover food compromises the water quality. A rule of thumb is to feed often, but little, and each feed should be eaten within 10 minutes. The leftover will go to waste.

3. Stirring

If you have a sand filter, you MUST stir the sand each week and backwash – do not treat it like a pool filter and backwash once in a while.

4. Quarantine for new fish

When buying new fish, it is important to quarantine the fish before introducing them to your pond. If you do not have this facility, then ideally get advice from a koi health specialist, as there are medications you can use, and a follow-up microscope analysis, to check the water balances.

5. Find the root cause

When there is trouble in the pond, please don’t medicate the pond in general and hope the problem goes away. You need to find the root of the problem, and then medically treat the problem. This will save you money and heartache from potentially losing fish.

6. Problem indicators

There are a few tell-tale signs that indicate problems with the fish. Look out for the following:

  • A fish who remains at the surface gulping is indicating that he has difficulty breathing – it can possibly be a problem with the water quality or parasites.
  • A fish flicking in the water indicates parasites.
  • A fish with clamped fins for a prolonged period indicate that he needs urgent help.
  • A fish who has heavy mucous indicates parasites.
  • A fish with growths and ulcers indicate bacterial infections.

There are other indicators as well. The bottom line is if you spend time with your swimming pets, you will notice a difference in the fish that could indicate potential problems.

7. Filtration

Filtration is critical and you can never have too much filtration in the water. It is important that your system turns over the water at least once an hour. In my opinion, the ideal is twice an hour.

8. Pump size

Buy the right sized pump as this will ease your electrical bill, and the water will flow easily with little effort.

9. Quality food

Feed your fish good-quality food. I often use the example of dogs – when feeding your dogs poor-quality food, the garden is soiled with dung piles and the dog receives little nutritional benefit. But when you feed them good-quality food, your garden looks much better because the dogs retain the nutritional value. In fish ponds the ‘dung piles’ from the fish form toxins in the water.

10. Aerate the pond

It is important to have sufficient aeration in your pond, either by waterfall or air pumps, to ensure enough oxygen in the water.


If you spend enough time with your fish, you will notice if there is a problem either in the water or with the fish. Keep the water balance ideal, feed your fish quality food, and if there is a problem, contact a koi health specialist.


Get The Latest Updates

Subscribe To Our Monthly Newsletter

No spam, notifications only about new products, updates.
On Key

Related Posts

Your winter pet checklist

Do you also, at times, suddenly stop and wonder where the year has gone? With so many goals to achieve and things to do, like

Q & A: Favourite bed

Q: What is the easiest way to get my dog to love his bed? A: First we need to establish what your dog loves in