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What Does "In System" Mean?

You've likely noticed several different types of feed mentioned in other sections discuss "In System Growable" ingredients, but what do we mean? The term we are using here would refer, in theory, to a system similar to an aquaponic operation.

 

Take for example, growth of Wolffia for the purpose of use in aquacultural feed (Said, 2022). This aquatic weed, sometimes referred to as Duckweed, has been demonstrated to be viably grown within both indoor and outdoor water tanks utilizing water with hydroponic nutrient inputs (Said, 2022). The proposed idea of "In System" coupled with this information would be that for an existing aquacultural or aquaponic operation, water with available nutrients from fish waste could be utilized as a growing medium in separate tanks for Wolffia intended for feed use. There would be some necessary separation between fish and plant to prevent clogging of filters and pipes and allow for ease of harvest and water cleaning prior to any recirculatory efforts.

 

The statement of potential for "In System Growable" does not attempt to make the statement that these ingredients can be grown directly within aquacultural tanks inhabited by fish, but that, given further research, engineering and based on current evidences, the listed ingredients have the potential to be grown alongside current aquacultural productions within the same facility utilizing similar resources and materials.

Photo Provided by Aquasol International

Image provided by Aquasol International 

What is Aquaponics?

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"Farm manager in Togo holding a 9 month old red tilapia." Image provided by Aquasol International 

FAO (2014) describes Aquaponics as, "...a technique for combining hydroponics and aquaculture in a system that cultivates plants in recirculated aquaculture water." 

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Aquaculture utilizes tanks of water to house and raise fish, this water naturally accumulates waste products from the fish which, to provide a brief description, is largely composed of ammonia. This ammonia based waste is not utilizable by plants and if allowed to build up within the tank can be dangerous if not fatal for the fish, but direct expulsion of raw fish waste into the surrounding environment can have negative impacts.

 

Aquaponics utilizes something called a biofilter, intially the wastewater is run through a mechanical filter to reduce levels of solid wastes, which still leaves a large level of ammonia within the water. The water is then filtered through a biofilter or "living" filter which is inhabited by large quanities of bacteria which convert the ammonia into nitrate through nitrification. Nitrate is usable by plants for growth and development, so the biofiltered water is then pumped into a hydroponic system and utilized to grow various plants and crops. This system removes a potential pollutant from aquacultural production and provides an organic source of fertilizer for soil-less crop production (FAO, 2014). The button below provides the full article by FAO (2014) for further reading and citation.

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Aquasol International

Aquasol International is a non-profit aquaponics based organization founded in 2016 by Phil Reasons and based out of Florida. They operate a production level aquaponics facility and provide valuable education, courses and facilities to areas in need of more sustainable farming practices and innovations and were a contributor for this webpage.

Their "Who Are We?" page speaks for itself about their values and mission,

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"At Aquasol International, we're passionate about making a difference in the lives of farmers around the world. We believe that sustainable farming techniques and technologies can transform communities, and we work tirelessly to provide the training and resources necessary to make that happen... ​At Aquasol International, we're proud to be making a difference in the world. Join us today in our mission to empower farmers and transform communities with sustainable farming practices."

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Click the button below to go to Aquasol International's Homepage!

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Image provided by Aquasol International 

Ingredients with the Potential to be Grown In System

Wolffia (Wolffia)

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Wolffia is a type of aquatic plant that contains necessary amino acids and 45.54% protein, making it an excellent plant based protein source. Wolffia contains 15 types of amino acids, 9 of which are Essential Amino Acids as well as various minerals, carotenoids and Vitamin E giving it good nutrient composition (Said, 2022).

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Wolffia In System

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Wolffia also has a rapid growth rate within an aquatic system culture making it an idea candidate for an aquacultural feed ingredient that could be grown within a base aquacultural, hydroponic or aquaponics system or tanks utilizing filtered water from these systems for nutrients (Said, 2022). 

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As a fast growing aquatic plant, azolla has great potential to be produced In System utilizing a setup similar to aquaponic systems or being grown in separate tanks using filtered water from recirculating aquacultural practices.

Azolla In System

Azolla (Azolla)

Azolla is an aquatically grown plant genus with several species. Azolla grown within Kamel (2026) that contained up to 35% crude protein, Azolla also has potential to be grown within an aquacultural setup. It has one of the fastest replications of any aquatic plant taking just 2-5 days to reproduce, significantly increasing its potential for sustainable use. It is stated to contain anti-nutritional compounds but supplementation with exogenous enzyme can help mitigate these impacts. 260 Tilapia with an average weight of 12.08 grams were used in Kamel (2026). In studies Azolla is shown to be able to replace fishmeal up to 30% without any negative health consequences for Tilapia and actually, azola fed fish were demonstrated to have higher crude protein and crude fat percentages in carcass than other feed sources (Kamel, 2026).

Further information about Azolla and its potential as a feed source for other species of fish, some with inclusion rates up to 42% for Nile Tilapia and up to 40% for Rohu, Labeo rohita can be found within Mosha (2018). The study also states that in general utilization of glycogenic amino acids is increased in fish fed a percentage of their diet containing Azolla. (Mosha, 2018)

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More resources and evidence for the potential for azolla can be found within Magbanua (2014) as it discusses successful studies where Azolla meal was fed up to 42%, but interestingly also highlights a study where it was not successfully fed, demonstrating the need for further research to determine ideal ratios as not all scientific studies agree.

Tadpole Meal

Hindatu (2017) is a study on Bufo maculate tadpoles that were raised for the purpose of being turned into meal after 84 days. The whole tadpole meal was then included into an experimental diet to determine its potential as a fish meal replacement for Clarias gariepinus fingerling production. The study revealed that no significant difference was found when tadpole meal substituted fish meal at 25-50% inclusion rate, with economic benefits being highest 25-50% inclusion rate, determining this to be a recommended amount for tadpole meal use in aquaculture providing economic and sustainability benefits as well as the potential for certain setups to grow their own protein sources. 

Tadpole Nutrition Requirements

Along with conversation on the idea of growing tadpoles within the framework of an established system the question of what this would even require is a natural jumping off point. Feed is typically the number one concern with these concepts, therefore a bit of discussion on what it is that tadpoles need to be grown is necessary. discusses the nutritional needs of tadpoles and their impact on the ecology surrounding them. Montaña (2019) discusses and reviews what tadpoles eat and the nutrients they require. It labels them primarily as herbivores and detritivores within this larval stage, stating, "algae and protozoa exhibiting the highest frequencies of occurrence in tadpole diets." It is mentioned that some do consume insect larvae and other tadpoles at times. There are several nutritional sources listed for tadpoles including: leaf litter, aquatic vegetation, insect larvae, microbes, detritus. The importance of this studies inclusion is that it provides parameters for Hindatu (2017) and its implications for rearing tadpoles as a protein source. The article demonstrates the opportunity to grow tadpoles largely on algae and detritus or sludge from other areas of production (especially for aquaponics operations) which could have significant impact on feed for aquacultural production if applied well.

Tadpoles In System

Tadpoles are noted to have similar production environment requirements to fish prior to metamorphosizing and therefore have potential to be raised within an aquacultural system setup similar to fry or hatchlings raised separately but within the same facility as adult and growing fish utilizing the same resources (Hindatu, 2017).

Citations

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Disclaimer

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The information provided by this website is for educational and informational purposes only. We are not responsible for any losses, damage or liabilities that may result from the use of this website or its contents. 

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This website and its contents are not affiliated with Kentucky State University and information provided does not reflect the opinions of Kentucky State University faculty and staff.

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