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The Goldfish Gazette, Issue #099 Aquaponics in Ponds
March 31, 2022

Goldfish Care Tips

A Free Monthly Resource For Goldfish Enthusiasts
March 2022
Issue #099

In This Issue
Aquaponics in Ponds

Aquaponics is a simple way to keep water quality high for your fish with the added benefit of producing edible plants.

Aquaponics in Ponds

Aquaponic Planting Trays In Pond

What is aquaponics?

It is a combination of hydroponics (growing plants without soil) and aquaculture (raising fish).

Fish waste provides food for the plants, and by feeding on the waste the plants maintain good water quality, reducing the need for water changes.

Green Pond Water Benefits

I once read that the ideal pond water to keep Goldfish in was water that was colored light green from algae.

In the past, I have always changed my pond water once it started to go green.

When climate change created water shortages where I live, I decided not to make water changes and instead closely monitored water parameters.

What I found was the pH didn’t drop, staying around 7.4 and nitrates were less than 5 ppm (parts per million).

This was an excellent outcome for the fish, but not for me. I can’t see the fish clearly, and algae can be a bit random, with the algae in some ponds disappearing completely, while others turning quite green.

Aquatic Plants Versus Aquaponics

The obvious answer to removing nitrates from my ponds is to use aquatic plants instead of relying on algae, but there are some disadvantages.

Many aquatic plants such as lilies and water hyacinth are seasonal so die off during autumn leaving large amounts of waste that needs to be removed before winter.

Goldfish will eat many aquatic plants limiting the varieties you can grow.

Aquatic plants can quickly take over a pond, or conversely, fail to thrive.

With aquaponics, plants can be grown away from the pond with water circulated through the planting tray using the filter pump, or a planting tray can be floated within the pond.

The advantage of this setup is you can grow edible plants such as watercress, which is considered a superfood, herbs, or any number of other vegetables. You can change the plants according to the season, and your Goldfish can’t get to them.

If you have a disease outbreak and need to clean a pond out, it is an easy task to sterilize the planting tray and growing medium (usually gravel), and it is no great loss to replace the plants you were growing.

A floating planting tray is easy to remove for water changes but the main reason for installing an aquaponics system is to not have to make water changes.

During winter you would just leave the tray out of the pond until spring.

Growth Inhibitor or Enhancer?

Maintaining ideal water parameters is going to keep your fish happy, but one issue could be the build-up of growth-inhibiting hormones.

Water changes will still have to be made if growing young fish, but I have read that fish kept in aquaponic systems tend to grow large quickly, inferring that the plants counteract growth-inhibiting chemicals in some way.

I will be testing this theory as my experiment with young Celestials kept in green water with low or no nitrates and no regular water changes hasn’t resulted in good growth rates.

I have set up some in-pond planting trays in two of my ponds that I will populate with watercress. I am using watercress because it is easy to grow and has a long growing season.

As with anything to do with nature, the trick will be to see how much watercress I need to grow in the ponds to maintain water clarity and keep nitrates low across a variety of fish populations and seasons.

Comments? Ideas? Feedback? I'd love to hear from you. Just reply to this e-zine and tell me what you think, or what topics you want to be covered.

Next Month's Topic

Issue 100, 8 years in Review

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