## How do I know how many fish I can have in my pond? | Decorative Ponds & Water Gardens Q & A

Q: How do I know how many fish I can have in my pond?

Lynn – Leitchfield, KY

A: Fish are like potato chips: It’s hard to have just one. When you visit your local pet retailer or water garden center and see those goldfish and koi staring up at you through the water, how can you not take them home!

Too many fish in a pond, however, can create an unhealthy environment for your fish and a breeding ground for algae. The more fish you have, the more waste they produce – and that waste can turn into algae fertilizer unless you have the filtration power to pump it out.

Before you start buying bucket-loads of finned friends, figure out how many you can comfortably keep in your pond. Here’s how in five simple steps.

1. Calculate Pond Size

First, determine the square footage of your pond’s surface area by measuring its length and its width, and multiplying the two numbers. We recommend no more than 1 inch of fish for every square foot of surface area, so if your pond is 250 square feet, that’s a maximum of 250 inches of adult, fully grown fish. If you need help with the math, use our online calculator. You’ll just need to know your pond’s length, width and average depth.

2. Allow Room to Grow

If you’re starting with young or adolescent fish, don’t max out your fish volume right from the start. Remember that those little guys will grow – a 2 inch fry will turn into a 10 inch adult in no time – and they’ll produce more waste as they develop. Skip the guessing game of growing fish by stocking adults, such as those included in our koi packages. You’ll enjoy instant gratification and a pond full of colorful fish!

Whether you’re starting with young fish or adults, add just a handful at a time. Your pond will need time to “season,” or build up its biological filtration system (a.k.a. beneficial bacteria), to handle the new influx of fish waste. Introduce a few fish, and then wait several weeks before adding more. While you’re waiting, give your biological filter a boost with DefensePAC® Pond Care Package. It contains Nature’s Defense®, Clarity Defense® and Muck Defense® – all of which promote the growth of those beneficial microorganisms.

4. Keep Up with Routine Maintenance

Once your fish have moved in, help them feel right at home. Use natural bacteria to break down fish waste, uneaten food and other debris. Provide shade, habitat and safety with floating and submerged aquatic plants. Feed them a healthy diet, like The Pond Guy® Staple Fish Food, which has the right amount of protein to keep them healthy without producing a lot of excess waste. Provide a healthy ecosystem and tasty food, and you’ll have a pond full of happy fish!

A external pressurized filter like the AllClear™ PLUS can handle excess waste, thanks to its powerful combination of biological, mechanical and ultraviolet filters. Its backflush option makes it easy to clean, and it’s easy to install in an existing pond because the plumbing doesn’t need to be run through the liner.

Or if you want to upgrade your entire water feature, check out one of our Pond Kits. Available in several different sizes, they contain a pump, pressurized filter or waterfall filter, pond liner, underlayment, plumbing, foam, hardware and beneficial bacteria to jump-start your biological filtration. All you’ll need to add is fish!

Pond Talk: What’s your most memorable experience with a fish overpopulation problem?

## Does Having Too Many Koi Cause String Algae? – Water Garden & Feature Q & A

Picture of String Algae.

Water Gardens & Features Q & A

Q: I have a bad case of string algae in my water garden and someone told me it was because I had too many fish. I have an approximately 1,000 gallon water garden and around 40 koi 6″ long in it. Is that really too many? If so, how many should I have? – Marco of Texas

A: You can ask anyone here at The Pond Guy; usually the first question we ask when someone says they have a bad algae problem is, “How many fish do you have?”, followed by, “What size water garden do you have?”. 9 out 10 times, there are way too many fish in the water garden. So why does having that many fish cause algae? Let me explain.

Sunlight + Food Source = Algae: Algae really only needs two things to grow, sunlight and a food source. The food source can come from many sources but fish waste is a major contributor. This means the more fish you have, the more waste, the more algae. Make sense?

Finding a Balance: When you put fish into your water garden always consider the future. Small fish become big fish and fish are very romantic creatures. Let’s say you purchased 20 koi at around 3″ each. Your pond may be able
to handle the fish load for a few seasons then all things start to change. As time went by, your fish have grown and maybe even started a family. As nature takes its course, your pond starts to pay the price and water quality becomes an issue. Take into consideration that 40 1″ fish produce the waste of just one 12″ fish. So even though you pond may have been able to handle the fish load in the past, you must consider that your fish load or fish waste grows expotentially every year.

Koi vs. Goldfish: I know that when you’re shopping for fish koi are more expensive and sometimes the goldfish look really nice too. I feel the same way myself at times. Just keep in mind that goldfish can reproduce up to 6 times a year where koi only reproduce once a year.

Fish Tips: Goldfish can grow up to 18” long and live up to 20 years, where as a koi can grow up to 36” long and live over 200 years! One famous scarlet koi, named “Hanako” (c. 1751 – July 7, 1977) was owned by several individuals, the last of which was Dr. Komei Koshihara. Hanako was reportedly 226 years old upon her death. Her age was determined by removing one of her scales and  examining it extensively in 1966. She is (to date) the longest-lived koi fish ever recorded (wikipedia).

POND TALK: How many fish do you have in your water garden?