Too much algae in the duck pond

Feb 13, 2025

Our duck pond at the Gobelo Farm in Hwange had been thriving. A perfect ecosystem where fish, ducks and dragonflies lived in harmony. The fish kept the water clean, the ducks floated (and splashed) about happily. Dragonflies danced above the surface and the weaver birds were converging with nests popping up in the nearby tree limbs - it was almost just too good. Everything was balanced. Until one morning, we found a dead fish floating on the water surface. Something had gone terribly wrong. The fish was a healthy bestowed weight, but fish shouldn’t just go belly up like that!!!

So of course, as we always do, the entire team got busy investigating the matter. And, we came to find out that algae is consuming all the oxygen in the water, leaving the fish (and the pond) gasping for air. Because of this, the fish died. Turns out that algae has been flourishing in the pond, because it feeds on the nutrients from the water and up until recently, we’ve been relying on the fish to keep things balanced.

But our duck family is growing RAPIDLY. We’re up to 113 ducks now (yes, you read that right). We estimate that our duck pond has a carrying capacity of about 90 ducks. All that ducks excrement settles at the bottom of the pond, giving the algae an abundance of nutrients to thrive. The fish being part of the ecosystem do feed on the duck droppings before they even hit the bottom, but there are just too many ducks now and not enough fish to keep up.

Apparently, and to our short lived relief, dragonflies eat algae, but the ducks are now gobbling up all the dragonfly eggs as well. It’s a chaotic cycle that we’ll have to find a way to balance. We’re now exploring solutions to counter the green takeover of algae, having experimented with a range of other ideas, including expelling buckets of water and using them in our gardens (to be replaced with fresh water), but that only seems to freshen up the pond for more algae plus it means we would lose smaller fish that would be carried away from the pond in the expelled water. We’re now looking into oxygenating plants, but the challenge there is finding plants that the ducks won’t eat - or we might have to figure out how to restore the dragonfly population (despite the ducks being villains).

It’s a balancing act. And right now, the scales are tipping in favour of the ducks... and the algae (and weaver birds).  Wish us luck as we continue to try to bring harmony back to the pond!