When passion meets persistence, remarkable businesses are born. I recently had the opportunity to sit down with Dean Deimler, owner of Koi Fish USA, to discuss how he started his company, how he continues to grow it, and what fuels his dedication to koi fish. Listening to his journey gave me a deep appreciation for his life’s work. His story is both inspiring and instructive for anyone striving to build something meaningful of their own.

Origin Story and Background

 

What first sparked your interest in koi and goldfish?

They’ve been a hobby of mine since I was a little kid. My dad built me my first pond when I was around eight years old, and that’s really where it all started. We upgraded and expanded it several times while I was growing up. Those early projects taught me a lot — not just about fish, but about responsibility, patience, and building something from the ground up.

How did you first get started and what was your original vision?

My original vision was to buy bulk baby koi and grow them out to sell. We quickly realized that was extremely time consuming, required a lot of space and labor, and wasn’t very practical at scale. So we pivoted and decided to purchase and sell fish that had already been grown out to certain sizes. That allowed us to focus more on quality control, customer service, and building the brand.

What were some of the biggest challenges you faced in the early days?

There were a lot of challenges. I had to learn fish health from scratch — understanding parasites, bacterial infections, water chemistry, and quarantine protocols. I also had to figure out how to safely package and ship live fish across the country without losses. On top of that, I taught myself how to build every iteration of our websites over the years. I really didn’t have a mentor showing me how to do this. We did get bits of help from various vendors along the way, but most of it was trial, error, and persistence.

Was there a specific moment when you realized this could become a serious business?

Yes. Around year six or seven, our sales tripled in a single year. My “side business” made more than my full-time job. That was a major turning point. That same year we were able to secure strong discounted rates with UPS for Next Day Air shipping, which dramatically improved our competitive advantage and allowed us to ship much more cost effectively. That's when I knew this wasn’t just a hobby anymore.

The Business Model and Growth

What makes your online store different from other koi sellers?

Two major things: volume and transparency. We sell a very high volume of fish, and customers can view and purchase the exact fish they’re buying. There’s no “representative photo.” What you see is what you get. That builds trust and sets us apart.

How do you source your fish? Do you work with specific breeders or farms?

We currently source all of our fish from Aquamade in Israel. They are raised indoors under strict biosecure conditions. The health quality is unmatched. These are some of the healthiest fish in the world because of the controlled environment and rigorous standards used in raising them.

How do you ensure quality and health before shipping?

All fish go through a rigorous 2–3 week quarantine process when they arrive. This allows them to recover from international transport and gives us time to monitor them closely. During quarantine, we observe behavior, monitor water parameters, and proactively treat for any pathogens that may arise. Only strong, healthy fish are approved for sale.

What does a typical day look like for you?

At this stage, my role is much more focused on management and oversight than day-to-day physical operations. I oversee the team responsible for fish care, packing, shipping, customer service, and inventory management. My day typically involves reviewing performance metrics, coordinating logistics, making purchasing decisions, troubleshooting operational issues, and ensuring our systems are running efficiently. I stay closely involved in high-level decisions — vendor relationships, shipping strategy, website improvements, and long-term growth planning — while trusting my team to execute the daily processes. Building and managing a strong, reliable team has been one of the most important parts of scaling the business successfully.

At what point did you know the business was truly successful?

When we had consistent year-over-year growth and repeat customers who trusted us enough to come back again and again. Success wasn’t just revenue — it was building a reputation where customers recommend us to others without hesitation.

Shipping Live Fish

Shipping live fish can be risky. How do you safely transport koi and goldfish across the country?

Fish are shipped in custom-made, double-wall corrugated boxes designed specifically for live transport. We only ship Next Day Air via UPS because they are extremely reliable and rarely experience delays or damage. That reliability is critical to our success.

What steps do you take to minimize stress during transit?

We pack as late in the day as possible to minimize the amount of time fish are in the box. Due to our shipping volume, we have a dedicated air driver who picks up our packages and takes them directly to the airport. This reduces handling time and keeps stress as low as possible.

What advice would you give customers receiving live fish for the first time?

Proper acclimation and quarantine are critical. Take your time adjusting temperature and water parameters before releasing them. Always quarantine new fish before introducing them into an established pond. Monitoring water quality closely during the first few weeks makes a huge difference in long-term success.

Fish Expertise and Care

What are the most popular varieties of koi you sell?

Butterfly koi are by far the most popular. Customers love the metallic colors and long, flowing fins. They make a strong visual impact in any pond.

What should beginners know before buying their first koi?

Learn how to monitor and manage water quality. A healthy environment dramatically reduces the chance of losses or disease. Understanding ammonia, nitrite, nitrate, and pH is essential.

What are the most common mistakes new pond owners make?

Overstocking or adding too many fish too quickly. A new pond’s biological filtration takes time to mature. If you rush it, water quality can decline fast and cause unnecessary losses.

How do you educate customers about proper fish care?

We are constantly adding and updating articles on our website. Education reduces problems for customers and helps ensure their long-term success. The more informed the customer, the better the outcome for the fish.

Scaling and Success

Did you bootstrap the company, or did you seek outside funding?

We bootstrapped it. We’ve grown slowly and steadily on our own over the last 22 years without outside funding.

What systems or tools have been essential to your growth?

Strong shipping partnerships, inventory photography systems, water quality monitoring systems, and continually improving our website platform. Operational efficiency and logistics systems have been just as important as marketing.

What advice would you give someone wanting to start a niche online business?

Be prepared to do everything yourself in the beginning. Learn your product inside and out. Focus on customer trust and reputation before chasing rapid growth. And be patient — consistency compounds over time.

What would you do differently if you were starting out today?

I would focus on digital marketing earlier — SEO, content marketing, and email retention. Building an audience sooner would have accelerated growth.

Passions and Personal Connection

Do you have a favorite koi?

Ochiba Shigure.

What do you personally love most about this industry?

The combination of art and biology. Koi are living art. Watching them grow and develop over time never gets old.

Have you had any memorable customer stories?

Many customers send photos of ponds they’ve built around the fish they purchased from us. Seeing someone transform their backyard into a peaceful space centered around koi is incredibly rewarding.

What keeps you motivated during challenging times?

The long-term vision. I’ve been doing this for over two decades. Challenges are temporary, but building something lasting keeps me focused.

Where do you see the business five years from now?

Continuing to scale responsibly, improving logistics even further, expanding educational resources, and strengthening our position as one of the most trusted online koi retailers in the country.

Industry Perspective

How has the koi industry changed in recent years?

Online sales have grown significantly. Customers are more educated and expect transparency. Biosecurity and fish health standards have also become much more important.

What does sustainability look like in the ornamental fish industry?

Responsible breeding practices, controlled indoor systems, proper quarantine, and minimizing loss during shipping. Sustainability means producing healthy fish efficiently while minimizing environmental impact.

How do you maintain ethical sourcing practices?

By working exclusively with reputable breeders who maintain strict biosecure facilities and high welfare standards. Health and humane handling are non-negotiable for us.

Questions for Fun

If someone had to describe you in three words, what would they be?

Persistent, disciplined, self-taught.

What’s one thing people would be surprised to learn about you?

I built every version of our website myself over the years without formal training.

If you weren’t running this business, what would you be doing?

Probably building or growing something else. I’ve always been wired to create and scale things from the ground up.