Build a Backyard Fish Pond: A Step-by-Step Guide

One of my most memorable experiences was a week in Hawaii for my brother's wedding—resort beaches, sunshine, mai tais, morning ocean swims, waterfalls, and the abundance of shimmering koi ponds everywhere. Glimmering white, orange, and black fish the size of party subs were at my fingertips. For me, the most peaceful, tranquil, and inspiring home landscapes incorporate a fish pond.

What does it take to put a fish pond in a backyard? Dallas landscape designer Harold Leidner, who has built dozens of ponds up to a $40,000 koi pond the size of a swimming pool, offers guidance. The takeaway: like indoor aquariums, fish ponds aren't for the faint of heart. They require time, effort, love, and care—can be time-consuming, budget-draining, and heartbreaking (losing any pet is tough). But the payoff is worth it. With just one free weekend, you can build your own backyard fish pond for about $2,500.

1. Dig the Hole

You'll need a big hole. Free if you DIY; dirt hauling costs a few hundred to several hundred dollars. Leidner prefers deeper holes, but aesthetics dictate depth. Both shallow and deep ponds have pros and cons.

Advantages of Shallower Ponds (1–1.5 ft)

• Less excavation, lower construction costs and backaches.
• Better view of fish.
• Water plants like lily pads thrive; they can't grow in deep water.
• Smaller ponds take less space and allow design flourishes.

Advantages of Deeper Ponds (5 ft)

• Fish grow to full potential (koi can reach 3 ft).
• More water volume = cleaner water, healthier fish, easier chemical balance.
• Fish are harder targets for predators (birds, raccoons, cats).

2. Line the Hole

Dirt holes don't retain water. Three popular methods:

Gunite (Spray Concrete)

Commonly used for pools. Leidner used it for a $25,000 Dallas pond.

Pros: Long-lasting, durable; creative lighting and design elements easy to include.

Cons: Cost—professional installation minimum $5,000 for average pond (includes pump parts and labor, not fish).

Rubber Liners

Strips rolled out, sealed, and used to line excavated hole. Rocks and design elements added on top.

Pros: Common, fairly inexpensive. Prepackaged pond kits $850–$1,500.

Cons: Difficult to install; mistakes cause drainage problems. Burrowing rodents can nibble through.

Expert tip: Buy a few bags of concrete, poke holes, line the hole, spray with water, then place rubber liner on top. Bags dissolve, concrete hardens, creating rodent barrier.

Premade Plastic Tubs

Good alternative, starting around $800, but limited shapes and sizes.

3. Install Pump Equipment

Available at local pool/pond supply companies with instructions. Hide under rocks/plants or purchase extensions to conceal on house side.

4. Add Landscaping

Budget for rocks, plants, or decking. Once everything looks good, add water. Check chemical balance and temperature before adding fish.

5. Add Fish

Koi are popular, but Leidner recommends fancy goldfish—ornate patterns and colors similar to koi, less aggressive, less expensive. Koi: $200–$7,000 each; fancy goldfish: ~$35 each.