“Have a banana, Hannah,” Cab Calloway sang.*
“Try the salami, Tommy.
Give with the gravy, Davy.
Everybody eats when they come to my house.”
Outside my bedroom window, where I see it when I wake up each morning, is a miniature fish pond whose inhabitants all seem to be singing along with Cab. Everybody eats when they come to my pond, and I don’t even have to feed them. In fact, they feed us.
It’s amazing how little it takes to make a sustainable system – how little, in terms of how few species and how little knowledge. Of course, it helps that the ecosystem is only about 20 cubic feet.
Ingredients for a pond
We started with a problem – mosquitoes – and, in good permaculture style, turned it into a solution – a pond. Mosquitoes preferentially lay their eggs in the pond (if no standing water is available, they’ll lay their eggs in a puddle or even a drop of water). To vacuum up the mosquito eggs, we added the second ingredient – nine goldfish. Two of them are visible in the picture if you look carefully. The goldfish also eat mosquito larvae and pupae, so if they miss any eggs, they get a second and a third chance.
Fish, of course, produce fish poop. To absorb the ammonia, nitrates and nitrites in the fish waste, we added water hyacinth, an attractive plant that you can see floating on top of the pond, as well as some submerged plants such as anacharis, which you can barely see. The fish nibble on the water hyacinth roots and on the submerged plants.
Water hyacinth is amazingly prolific – it can be an invasive nuisance but also holds potential as a biofuel for the same reason – and in spite of the goldfish nibbling, it spreads quickly, threatening to block all sunlight from the pond. It’s edible, and is eaten in some places, but we haven’t tried it yet. I have tried feeding it to the rabbits, though, who were most appreciative.
We added two other plants that are fertilized by the fish waste but don’t give anything back to the fish – a watercress (left-hand pot) which is not only edible but actually gets eaten, and a hibiscus (right-hand pot) which makes glorious orange flowers, only not right now. Hibiscus flowers are edible, too, but I get more enjoyment out of looking at them.
The flowerpots accumulate small amounts of algae, which, like the plants, both filter the fish wastes and provide food for the fish. And the cinderblocks that the pots sit on shelter the fish when they need to hide from birds or other predators.
Regular visitors to the pond include four green frogs, one of which is on a rock at the left side of the picture. They’re well camouflaged – they always seem to be exactly the color of the leaf or rock they’re sitting on – and they spend most of their time waiting patiently for something edible to fly by. As far as I can determine, they don’t eat mosquitoes (too bad!), but beetles, flies, grasshoppers, butterflies and moths are all fair game.
Frogs also eat small fish – and I can’t say for sure that they haven’t eaten some of my fish – but for them the pond is not so much a food source as an escape hatch. When they hear me approaching, they dive into the water and hide almost before I’ve seen them. The pond is also where they lay their eggs. I haven’t seen any tadpoles yet, but that may just be because the black pond liner makes them hard to see. Or it may be because the tadpoles (which eat algae) are getting eaten by the goldfish. Some say goldfish will eat tadpoles only as a last resort, but of course, the goldfish aren’t reading discussion forums on the Internet and may well have their own opinions.
As Cab Calloway put it,
“Don’t be so picky, Micky,
‘Cause everybody eats when they come to my house! ”
*Lyrics are by Jeanne Burns even though Calloway made them famous.