Aquaponics systems are becoming more and more popular as additions to permaculture gardens. In fact, they are becoming increasingly important in the struggle to create more efficient and green methods of producing food. By allowing two harvests – of plants and fishes – as well as generating significant economies of energy input, water use and space, aquaponics systems may well have a claim to be one of the food production systems of the future – the beauty being that they already exist in the here and now. (Of course, aquaponics methods of agriculture have played a part throughout human history and remain important to many cultures, but remain relatively unutilized in the West.)
If you are considering establishing an aquaponics system as part of your permaculture plot, one of the key decisions you will need to make is which species of fish to stock it with. There are lots of factors that will come into play when making this decision – everything from what type of food the species needs, how it interacts with plant roots, their size and, of course, what they taste like. And, as with other permaculture systems that you institute, a thorough analysis of the needs, products and inherent characteristics of the fish should be done as well. Some of the criteria to consider when doing an analysis of fish species are whether the fish is suited to living in enclosed tanks, how resistant to disease the species is, what water conditions it needs (and what you can provide), and whether they are available for purchase near you.
However, there are certain species of fish that have proved to be particularly adaptable to aquaponics. Here we highlight some of the species that aquaponics practitioners have enjoyed success with.
Arguably the most common aquaponics species, tilapia are ideal candidates for the novice. They are very easy to breed, will thrive even in sub-prime water conditions, are omnivorous – meaning they eat algae, among other things, helping your system stay clean – and are very tasty on the plate. One note: they do require warm water, so a greenhouse system is best. There are actually more than one hundred species that make up the tilapia family, but the Nile tilapia is the most extensively farmed, due to its rapid growth and good size at harvest.
In contrast to tilapia, trout thrive in cooler water temperatures, so are perfect for outdoor aquaponics systems – a water temperature anywhere between ten and twenty degrees Celsius is fine. They are carnivorous so need fish-based food, insects and aquatic invertebrates as feed. Trout grow very quickly and have an excellent food conversion ratio – meaning you get more flesh to eat per fish for the amount of fish food you input into the system.
In previous centuries carp was one of the most farmed fish species across the world. It remains popular in parts of Eastern Europe and Asia, but has declined elsewhere. Fortunately, aquaponics and other agricultural innovations are managing to turn more people’s attention on these food eating fish. Omnivorous, carp thrive in a wide range of water conditions, making them a good choice if your plot has highly variable weather. Carp have a high reproductive capability, so you may be able to rear successive generations from you starter stock.
Catfish differ from the other species featured in this list in that they don’t actually have scales. That means that when you come to harvest them you would need to skin them – which is actually not as hard as it sounds once you’ve got the hang of it. Once skinned and ready for the plate, their high food conversion ratio means that you get lots of tasty, firm flesh. The channel and blur varieties of the species are particularly well suited to aquaponics systems as they have the broadest diets – including plants, insects and other fish – and are known for their high nutritional value.
You don’t have to incorporate edible fish in your aquaponics systems. Vegetarians or those who prefer not to harvest their own animals may want to consider koi. A species of carp, koi are common ornamental fish in Japan and have increased in popularity around the world as colorful, hardy animals that are adaptable to many types of water systems. Koi are renowned for their relatively long life span and their durability against parasites, meaning you will not need to replace your stock very often. Omnivorous, they will eat a wide range of foods, including algae from plant roots.
Perch are actually one of the healthiest fish to eat. They contain high levels of omega-3 oils, an essential nutrient that can help improve cognitive function. There are several species of perch that suit aquaponics, the most popular being the jade perch. Omnivorous, they will eat zooplankton, crustaceans, insects, mollusks, algae and plant material. Jade perch also grow quickly and have a robust constitution. They do require warm water so an aquaponics system in a greenhouse would be an ideal environment. Silver perch are another option, although they are not as fast-growing as their jade cousins, typically taking between twelve and eighteen months to reach harvesting size.
The largemouth bass is a viable species for larger aquaponics systems. They grow to maturity relatively quickly and have a very varied diet, ranging from insects and crustaceans as juveniles to anything up to snakes and small mammals as adults! Fully mature bass are too large for most aquaponics systems and require a large amount of feed, but harvested at a more juvenile size, they have a clean – if strong – taste.
There are a number of crustacean species that can be utilized in an aquaponics system, either as a standalone or in combination with fish species. Freshwater prawns, crayfish and mussels are all viable options. Crustaceans give a different dimension to an aquaponics tank and adding some to your system can help keep the bottom clean – mussels are particularly useful as they are filter feeders, so help keep the water clean.