WELCOME TO NT KOI
SPECIALIST KOI SUPPLIERS
Premium, Hand-Selected Koi for Discerning Enthusiasts If you're seeking something truly special for your pond, get in touch—we specialize in supplying only the most selective, hand-picked koi of the highest grade.
Our koi are renowned for exceptional quality and health. The local environmental agency recognizes us as achieving the highest possible standards in koi healthcare, awarding us their top-tier 5-star rated animal welfare licence.
This certification reflects our unwavering commitment to the welfare, biosecurity, and wellbeing of every fish we supply. Contact us today to discuss how we can help you add exceptional koi to your collection!
If you are after something specific, we can help. Contact us with your requirements and let us find it for you
Business Hours
Available Every day
- Mon – Sun
- 09:00 am – 05:00 pm
Please contact outside these hrs if you have an urgent requirement
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All our services
Pond Builds & Upgrades
Expert Pond Design, Upgrade & Construction Services Whether you’re planning a brand-new pond build or looking to upgrade and modernise an existing one, we’re here to help every step of the way.
We guide you from initial concept through to completion, offering:
- Detailed 3D visualisation and design
- Expert general advice on layout, filtration, and stocking
- Full turnkey construction if required
Specialising in older ponds? We love bringing them back to life. If your pond needs some TLC—perhaps a filter upgrade, better circulation, improved water quality, or a complete overhaul—this is exactly where we excel.
Let us help you create (or restore) a healthy, beautiful environment that your koi will thrive in. Get in touch today to discuss your project!
Sleeper pond
Ponds Tailored to Your Vision – Any Size, Any Style Ponds can be designed in virtually any size and style to perfectly suit your space and preferences.
Whether you’re dreaming of:
- An elegant in-ground pond with a pumped filtration system, or
- A striking above-ground (out-of-ground) block-built pond with gravity-fed circulation,
…we can bring it to life.
We also specialise in custom features such as side viewing windows for a stunning underwater perspective of your koi.
One of our most popular designs is the classic sleeper pond – timeless, robust, and beautifully integrated into any garden setting.
Ready to create (or upgrade) the pond of your dreams? Get in touch—we’d love to discuss your ideas and show you what’s possible!
Wildlife & koi pond
Simple, Natural Koi & Wildlife Ponds Or if you’re looking for something more relaxed—a beautiful, low-maintenance koi and wildlife pond that blends seamlessly into your garden—we can create that too.
This example features a gentle waterway for natural flow and movement, surrounded by elegant decking that provides easy access for viewing and enjoying your fish and wildlife.
It’s the perfect balance of serenity, functionality, and natural beauty—ideal for koi that thrive in a peaceful environment, while also attracting birds, frogs, and other garden wildlife.
Interested in a simple, stunning pond like this? Get in touch—we’d love to design and build one tailored just for you!
Block built with window
Above-Ground Block-Built Pond with Viewing Window Featuring our popular “out-of-ground” design: a robust, block-built pond elevated for easy access and stunning visual impact.
This style includes a crystal-clear side viewing window so you can enjoy an up-close view of your koi swimming gracefully.
The system is fully gravity-fed to a high-performance drum filter, using:
- A generous 4-inch bottom drain for efficient solids removal and excellent circulation
- A dedicated skimmer line to keep the surface clean and debris-free
The result is a low-maintenance, high-efficiency setup that delivers crystal-clear water and a healthy environment for your fish—all wrapped in a beautiful, space-saving design that becomes a true focal point in any garden.
Love the look of this style? Contact us to discuss how we can custom-build one tailored to your space and vision!
View through the window
The Finished Look: Above-Ground Block-Built Pond with Viewing Window Here’s the completed view of our block-built, out-of-ground pond featuring the stunning side viewing window.
If you like the idea of a window, it truly transforms the experience—giving you a completely different, crystal-clear perspective of your koi swimming right at eye level. It’s not just a feature; it’s a beautiful way to connect more closely with your fish every day.
This design combines practicality, elegance, and wow-factor, making your pond a real standout in the garden.
Love what you see? Get in touch—we can create something just like this (or customised to your exact space and style)!
Air Source Heat Pumps
ThermoTec Air Source Heat Pump (ASHP) – Supply & Installation Maintain perfect control over your pond temperature year-round with a high-efficiency ThermoTec Air Source Heat Pump.
Designed specifically for koi and fish ponds, these reliable units keep water stable in all seasons—protecting your fish from temperature swings, supporting health, and extending the active feeding/growing period.
Available in a range of powerful outputs to suit every pond size:
- 9 kW – Ideal for smaller to medium ponds
- Up to 24 kW – Perfect for larger or heavily stocked systems
All models feature convenient built-in WiFi connectivity, so you can monitor and adjust temperatures remotely from your phone—anytime, anywhere.
We handle full supply and professional installation, ensuring seamless integration with your existing pond system for maximum efficiency and longevity.
Want consistent, crystal-clear water temperatures and healthier, happier koi? Get in touch today for expert advice, sizing recommendations, and a no-obligation quote!
Water Parameter Testing
The Importance of Regular Water Parameter Testing
Water testing is one of the most important ways to stay ahead of issues and keep your pond – and your koi – in peak condition. Regular monitoring gives you a clear, real-time picture of your pond’s health at any moment.
Key parameters should be checked consistently: some (like ammonia, nitrite, and kH / pH) are best tested weekly, especially in newer ponds, heavily stocked systems, or during seasonal changes. Others (such as nitrate, GH, or phosphate) can often be monitored monthly once the system is stable.
The exact schedule depends on your setup, stocking levels, and season—but the golden rule is simple: choose testing intervals that give you enough time to spot trends, make adjustments, and correct any problems before your fish show signs of stress or illness.
Consistent testing isn’t just good practice; it’s your early warning system for maintaining crystal-clear water, stable conditions, and thriving, healthy koi.
We’re happy to advise on the best testing routine for your specific pond, recommend reliable test kits, and help interpret results—just get in touch!
Microscopic investigations
Identifying parasites in a pond without a microscope is extremely difficult and often unreliable.
Attempting to diagnose parasite problems by eye alone usually leads to guesswork, which can be risky. Applying the wrong treatment may:
- Waste valuable time
- Delay proper care
- Harm fish or further stress the pond ecosystem
- Potentially make the situation significantly worse
Best practice: Whenever you suspect a parasite issue, always seek experienced, reliable advice (from a knowledgeable pond/aquatic veterinarian, fish health specialist, or laboratory that can perform microscopic examination when needed).
Visual inspection and behavioral symptoms can give clues, but they are not enough for an accurate parasite diagnosis in most cases. Microscopic confirmation remains the gold standard.
Correct identification → correct treatment → best chance of recovery.
Individual Koi treatment
Sometimes the issue isn't the whole pond — it's one (or a few) individual fish that need targeted help.
While good water quality and early parasite detection are essential for the overall health of your pond, certain problems show up in just one or a handful of fish. These cases often require:
- Separate observation and isolation
- Specific medications or treatments (dips, injections, topical applications, etc.)
- Careful dosing adjusted to the fish’s size and condition
- Supportive care (e.g., salt baths, temperature adjustment, improved oxygenation)
Trying to treat the entire pond for an individual fish problem can be unnecessary, expensive, stressful to healthy fish, and sometimes harmful.
We have the experience to help.
If you're seeing unusual behavior, lesions, flashing, clamped fins, rapid breathing, or other signs in one or more fish — even when the rest of the pond looks fine — reach out. We can guide you through:
- Accurate identification of the likely cause (based on symptoms, history, photos/video if available)
- Whether isolation and individual treatment is the better approach
- Safe, effective treatment options tailored to the situation
- When microscopic examination or professional lab testing is strongly recommended
Parasite identification
Parasites are a normal part of life in every koi pond
Healthy koi with low stress and a strong immune system keep parasites under control naturally, showing no signs of trouble.
Problems arise when immunity weakens — especially right after winter:
- Fish emerge tired and vulnerable
- Parasites multiply quickly
- Skin/gill damage follows
- Ulcers form
- Secondary bacterial infections (often deadly) set in
Best approach: Keep stress low and immunity high year-round with:
- Stable water quality (especially in spring)
- Gentle warm-up after winter
- Good nutrition
- Excellent oxygen and circulation
- Regular observation for early signs
Strong, low-stress koi rarely suffer serious parasite issues. If you spot flashing, sores, or fish acting off post-winter, tell us what you’re seeing — we’ll help you catch it early and handle it safely.
Pond treatment advice
Chemicals should only go into your pond when absolutely necessary.
Using treatments without knowing the exact problem can upset the natural balance, harm beneficial bacteria, stress or damage fish, and often leads to bigger issues down the line.
Key takeaway: Only add anything once you’ve confirmed what’s really wrong.
Prevention beats treatment every time:
- Do regular pond checks (weekly is ideal) — test ammonia, nitrite, pH, KH, temperature
- Watch fish closely for flashing, clamped fins, gasping, sores, or odd behaviour
- Look for algae spikes, poor clarity, debris, or filter problems
- Keep up good habits: sensible feeding, partial water changes, sludge removal, clean filters
Stable, clean water + consistent monitoring = healthy, happy koi with minimal need for chemicals.
If something doesn’t look right, let us know what you’re seeing (or your latest test results) — we’ll help you decide the safest, smartest fix, usually without reaching for a bottle.
3D Pond & garden design
Visualizing your finished pond and garden makes all the difference.
Seeing the completed project before any digging begins helps you:
- Confirm the layout, scale, and flow feel exactly right
- Spot any adjustments you’d like to make early
- Ensure the design complements your home, garden style, and lifestyle
- Avoid costly changes once construction starts
- Get excited about the transformation ahead
What we provide:
- A high-quality 3D video walkthrough of your proposed pond and surrounding garden — bringing the finished vision to life from different angles, showing water movement, planting, lighting, and overall atmosphere.
- Detailed 2D plans (if requested) including exact measurements, depths, filtration placement, electrical runs, planting zones, hardscaping details, and any other technical information needed for accurate quoting or construction.
These visuals give you complete confidence in the final result and allow us to fine-tune everything together before work begins.
If you’re ready to move forward, share a few details about your space (size, shape, style preferences, key features you want, budget range, etc.), and we can discuss how best to create your personalized 3D preview and plans.
We’re here to turn your dream pond and garden into something you can see — and love — today.
Complete solution for Home and garden renovations
Turnkey Garden Room & Water Feature Solutions If you're looking for a complete turnkey solution, we now partner closely with Collinwood Constructions to deliver everything under one seamless project management umbrella.
From initial design through to final delivery, we can transform your garden space with a stunning new garden room integrated with a koi pond or water feature—all packaged together for simplicity and peace of mind.
House Renovation & Construction Services Alternatively, if you simply need a reliable construction company for any home renovation project, Collinwood Constructions is ready to assist.
PRICING
POND MoT - £90 (Within 25 miles of Cambridge)
- This includes, full comprehensive water parameter check using latest electronic equipment.
- Microscopic scrape of up to 2 fish to check for parasites
- Discussion on the pond in general and the filtration system
- Advice on treatments or follow up visits required
- Any other advice
Extras during Pond MoT visit
- Topical Koi treatment £30 per fish
- Whole Pond Treatments £20 + medication cost
GENERAL CALL OUTS
- £60 (inc 1st Hr) + £30/hr thereafter
3D DESIGN
- Pond design video + precise measurements - £90
- (visit required for measurements)