We are driven by an instinct to care for, feed and nurture all living creatures. But we must recognize that some good intentions can lead to bad consequences.
But education can avoid irreversible outcomes.
If your pond is home to both koi and goldfish, recognize their different eating habits. Koi eat more...they simply require it. Less resourceful by nature, koi settle on the pond’s bottom and forage through mud and stone for meals. Goldfish, on the other hand, are clever and crafty - they will attack small prey or settle for fry, whatever may be available to consume.
The most common mistake in caring for fish is overfeeding. Koi emerge from their watery home at meal time. Always fun for the fish owner...not always best for the fish. Limit fish food to what they need. Overfed fish are at risk - with telltale signs of swollen bellies - and can suffer organ damage or death.
So respect the basic rules. Feed your fish for no more than five minutes per feeding, up to three times a day in cooler water (65-70 degrees), once a day in warmer water (76-82 degrees). Be aware of fish reaction when food is offered. If they are ravenous, feed up to five minutes. If there are no takers, be disciplined and stop serving.
If overfed, more than the fish will suffer. When fish eat...they excrete. The more they eat, the more they excrete. Fish excreta increases pond nutrient levels which can bring about an algal bloom and a decreased level of oxygen. Overfeeding will increase heterotroph bacteria - the organisms responsible for breaking down uneaten food, fish waste and dead plant matter into ammonia. Even in small amounts ammonia can impact the fish immune system and make them more vulnerable to infections.
Heterotroph bacteria need oxygen. As these bacteria increase, oxygen levels in the pond decrease and fish become stressed and sick. Warmer weather - which brings warmer water - can get tricky. Warmer water carries less oxygen but hungrier koi. Water quality becomes more delicate in warmer months.
If your pond is in protected shade part day - or receives just filtered sunlight - this will keep oxygen levels strong. Waterfalls can help ensure healthy oxygen levels and mitigate risk to fish and prevent an unhealthy - and unsightly - bacterial bloom. But aerators are the most efficient means to oxygenate your pond. OASE aerators pump air directly into your pond to quickly increase oxygen levels, are eco-friendly and energy efficient.
The best lesson is to pay attention. Test the water if you’re in doubt. Watch the movement and shape of your fish and water clarity and take appropriate action if changes are apparent. Time may be your best ally.