People always ask the question: are you a cat or dog person? But what if your answer is fish! …
Koi are among the friendliest fish, once they warm up to the environment, they allow you to feed them and may even leap out of the water to greet you! Because they are so active any small change in their behaviour is quite easy to spot and you can soon read their mood.
But what are their moods?

It might sound weird, but you can spot when your koi fish is happy, sick, stressed out or even in need of oxygen.

Once the fish have familiarized themselves with their surroundings and feeding schedule, they become quite active. If the same person feeds them every day, they learn to recognize them and grow comfortable enough to swim to the surface and eat out of their hands.

You can spot when a koi fish is stressed out by their movement or lack thereof. They are easily stressed by a change in pond, temperature fluctuations, or even a shift in water chemistry. They become lethargic and skip feeding, rub up against the side of the pond and this stress can even manifest in ragged or bloodshot fins. 

If the koi is stressed, they often become sick as with humans the stress weakens their immune systems. Darting around the pond or extreme sluggishness can be indicators. If their usual streamlined and elegant swimming looks uncoordinated or clumsy that can be a sign as well.
If there is less aeration in the pond that can result in less oxygen in the water. When this is the case, they often come to the surface gasping for air or leap to the surface. A water fountain or waterfall can help with this as they naturally oxygenate the water.

Familiarizing yourself with your koi is integral to them as well as the health of your pond, as they will always be the first to know if anything goes awry.