Written by Doug Crouch
High Quality Feeds
Fish, like poultry, do indeed prefer to eat insects rather than grains. However I will present both here but I do highly recommend growing insects for supplemental aquauculture (and poultry) feed. Bill Mollison also recommended this technique and can be viewed in the Aquaculture chapter of The Designers Manual on page 492. I myself have cultured insects and seen zealous response from fish and poultry with these fairly easy systems of growth. The unique thing about the culture of insects is that they are virtually all protein where as commercial or even homemade feeds are a mix of proteins and carbohydrates when grains are the main component of the feed. Also food scraps present this composition of a mix of proteins and carbohydrates and are often fed to chickens as well. However they can be upcyled with other life kingdoms with the final product being a high quality feed with very little inputs: maggots. Not only maggots can be cultured while taking advantage of easy to harvest waste streams.
Fly Larvae Production
Maggots, the larvae of flies, proliferate quite quickly and thrive in humid and protein rich environments. Some think it is absolute necessary to have meat or fish to attract and feed them but I have successfully raised them on just vegetable wastes. In fact quite often in compost piles or worm bins maggots are cultivated because of improper management that decreases oxygen content and increases humidity. When these conditions occur flies are attracted and lay their eggs. Systems should be created along with research on the particular flies of your area to know their gestation period. Meaning if you put a load of
food scraps into a bucket with holes on the sides, you should know how much time it takes for larvae to hatch into flies. Obviously you want to avoid this but also let them grow to a meaty size for optimal production. If their gestation period is 10 days after eight you can dump them in the water and watch the ensuing feeding frenzy. The other scraps that go in will be consumed by bacteria and benthic invertebrates thus feeding the food chain even more. There are also other systems that are continuous and let the larvae crawl out of the mass and into a shoot where they are captured (Bipod TM pictured above). They naturally do this when they are ready to hatch out of a carcass so a properly designed system will allow for continuous production and capture without a fly invasion. Furthermore some even just hang roadkill over a pond in a suspended mesh basket and as they grow and wriggle they simple slowly drop out into the water body and give trickle down feed system.
Worms can be a great way to convert vegetable scraps and carbon material such as cardboard into a rich fertilizer and a protein rich feed source. Worms are given a home where food can be added and humidity regulated. Worms want less moisture than maggots but will not thrive if their home becomes too dry. Food scraps are combined with brown material as to balance the carbon to nitrogen ration as to provide a healthy habitat for their thriving and your free feed resource. Over time, the worms populate and you can begin to harvest some for fish feeds. By harvesting them they will continue to keep reproducing in a rapid manner. Commercial operations require a different design differing from the normal trash bin or bathtub type of design for more household usage. However several of these smaller bins can supplement your feeding of fish and fowl if commercial scale is not needed. Remember of course for the important function of dealing with food scraps to have multiple elements as well as for the important function of feeding fish and fowl to also support it with multiple elements.
Other insects can be cultured or gathered in Nature to help feed fish and fowl as well. In Costa Rica In 2005/06, I would take my machete and hack into a termite nest on a tree and chuck that into the pond. The termites would be consumed as they floated on the water surface. The nest would regrow and months later I could do the same without harming their role in the ecosystem. Also other insects can be harvested in gardens by creating dry spots using newspaper. They hide in this easy to collect homes and then a simple harvest ensues by shaking the newspaper into a bucket and then throwing that into the pond. Furthermore, Mollison writes that a yellow painted circle can be extended over
the pond and grasshoppers will jump towards that but not always land on this landing pad. Upon their entry into water they will likely be consumed. Finally a light can be rigged over a pond just above a fan that blows night insects into the water for nocturnal consumption. Commercial ones are manufactured these days but they can also be a DIY project. Either way the insects blown in represent another way to feed fish and fowl protein rich feed with little input. If you are thinking to choose one of these, again remember the permaculture principle for the important function of … (feeding fish and fowl), support that with multiple elements. These should be done in relative location with a mind of zones and sectors and flows as to always be energy-efficient.
Fish Food Recipe
An in-house system of growing can leverage a permaculture through growing specific crops for producing your own fish food to fully utilize on site resources especially in malnutrition situations or whole systems design. To do so grow an appropriate grain for your climate (wheat, sorghum…) and harvest and process it. If all else fails you can purchase this in bulk but this recipe is meant for a whole systems design where the raw ingredients are provided through on site cultivation. Then grind the grain and mix it with a high pectin fruit (mango, banana, crabapple) to get it to bind together and balance the nutrients. Then put this through a meat grinder extruder to make a uniform shaped strand. The strands are fragile so handle carefully as you lay this on cookie sheets and sun dry. It is done when the outside is crunchy and inside moist which causes the feed to float. Cut into small bits according to fish size and record feeding amounts and store accordingly to keep rodents and insects away. Carefully monitor feed amounts so that no waste happens in the system as too much feed will not be consumed and then it falls to the bottom and is consumed by bacteria. This can lead to lower water quality as well and a discussion on the page water quality parameters of this website will help you with a deeper understanding.
Written by Doug Crouch
Header art by Sien Verpoest