How to Introduce New Koi to Your Pond Without Stress

Transferring new Koi fish to your pond is exciting. But without proper precautions, you could unknowingly expose your fish to harmful parasites, bacteria, or viruses that put your entire pond at risk. Here, we’ll walk you through a few simple steps to help your new Koi settle in safely and soundly.

Pre-Introduction

Before transferring Koi fish to your pond, keep them in a separate quarantine tank or tub. Although your new fish may look healthy, they often carry hidden parasites or diseases like Costia, Ich, or Koi herpesvirus—all of which can threaten the health and safety of your fish and pond. We recommend a 2-4 week quarantine period, during which you observe fish for any signs of illness.

Preparing Your Koi Pond

Assess Water Quality

Poor water quality stresses fish and increases the risk of disease. Before transferring new Koi fish, test the water quality, noting ammonia, nitrite, nitrate, pH, and temperature readings. Ideally, your readings should look something like this:

• Ammonia/Nitrite: 0 ppm
• Nitrate: Below 40 ppm
• pH: Between 7.0–8.0
• Temperature: Match as closely as possible to the quarantine tank

Evaluate Filtration System Capacity

Beyond water quality, make sure your filtration system can handle more fish. Why? Transferring Koi fish means more waste, more food, and more demand on your system.

In general, your filter system should be able to process the entire volume of your pond at least once every hour.

Add Hiding Spots

Here’s another Koi fish tip: give your new arrivals a few safe places to hide. This is especially helpful if you have territorial fish or a crowded pond. Plants, tunnels, and underwater features give new Koi a chance to settle in without feeling overwhelmed.

Introduction Day Process

Introduction Day is when all your prep pays off—but it’s also when your new Koi are most vulnerable. Here are a few Koi fish tips to help you minimize stress:

• Transfer at the right time: We recommend a calm, mild day. Avoid transferring Koi fish during extreme heat or cold.
• Delay feeding: A calmer environment means less curiosity, competition, and chaos when new fish arrive. Postpone feeding a few hours before transferring new koi fish.
• Slowly acclimate new fish: The key to a successful transfer is restraint. Never dump fish into the pond. Instead, float the transfer bag or container in the pond for 15–30 minutes to match the temperature. Then, slowly add pond water every 10 minutes. After 30–60 minutes, net the fish into the pond, but do not transfer the water (it may contain waste or pathogens).
• Monitor: Watch the new Koi for the next hour or two. They may hide at first, but this is normal. Common signs of trouble can be fish rubbing against surfaces, gasping at the surface, or bullying.

Build a Pond Your Koi Will Actually Thrive In

Building a healthy, low-maintenance Koi pond takes more than just digging a hole and filling it with water—it takes smart design, proper filtration, and an understanding of how fish behave. This is where we come into play. We’ve helped homeowners, businesses, and venues across San Diego create thriving aquatic environments since 2004, and we can do the same for you. Contact us today to get started.