Feeding biochar or charcoal increased the growth rate of striped catfish (Pangasius hypophthalmus) and improved water quality

Trinh Thi Lan, T R Preston¹ and R A Leng²

Angiang University, 18 Ung Van Khiem Street, Dong Xuyen Ward, Long Xuyen city, Angiang province, Vietnam.
ttlan@agu.edu.vn
¹ Centro para la Investigación en Sistemas Sostenibles de Producción Agropecuaria (CIPAV),
Carrera 25 No 6-62 Cali, Colombia
² University of New England, Armidale, NSW, Australia

Abstract

A 90 day feeding trial was conducted to determine the effects of biochar and charcoal on water quality and on growth performance of striped catfish (Pangasius hypophthalmus) raised in tanks.  The five treatments in a completely randomized design with 4 replicates were: NBC (no biochar or charcoal), BF (biochar in feed), CF (charcoal in feed), BW (biochar in water) and CW (charcoal in water).

Growth rates were increased 36% by adding biochar to the feed and by 44% with charcoal. There were no benefits from adding either biochar or charcoal to the water. In contrast, adding charcoal to the water had a negative effect on feed intake, growth rate and survival. The ratio of weight to length in the fish at the end of the experiment was 25% greater when biochar or charcoal was added to the feed, indicating an enhanced flesh to bone ratio due to the faster growth rate with addition of biochar or charcoal.  Levels of ammonia nitrogen (TAN), nitrite (NO₂^-, phosphate (PO₄^3-) and chemical oxygen demand (COD) in the tank water were reduced by adding biochar or charcoal to the feed, but not to the water. The role of biochar (and charcoal) in facilitating the formation of biofilms as habitat for gut microbiota could be the explanation for the improved growth rates recorded with biochar and charcoal added to  the diet. 

Keywords: biofilm, culture tanks, habitat, microbiota, survival

Introduction

Production and use of charcoal principally as fuel for household cooking and smelting of iron ore is a centuries-old tradition (https://en.wikipedia.org/wiki/Charcoal). However, it is also known, especially in Japan,  for the benefits it confers on soils for growing of vegetables (http://www.japanfarmersmarkets.com/2015/02/japanese-charcoal-how-and-why-this.html).

Biochar differs from charcoal in that the process of carbonization takes place in a more restricted flow of air and at higher temperatures (500 to 1000 °C). These are the conditions found in gasifiers be they updraft (TLUD) stoves for cooking (Olivier 2010) or downdraft reactors producing gas for internal combustion engines, turbines or simply process heat. By using fibrous waste as feedstock, the gasification system, and the associated production of biochar, avoids the conflict of using natural resources of soils and water for biofuels instead of food (Preston 2015).

To date most of the emphasis given to biochar has been on its role as an amendment in soils and its potential to sequester carbon (Lehmann and Joseph 2009). However, recent research shows that its role is much wider with potential application in all components of farming systems that involve microbial activities (Preston 2015).

Tra catfish ( Pangasius hypophthalmus ), a member of the Family Pangasidae, has high economic value, and has become one of the important fish species in Vietnam and other countries in the South East Asia region. This fish is raised in ponds, cages and fence culture (Chau Thi Da et al 2007). However, the farmers have changed from the cage culture to pond culture because the cost for the cage system is higher and the disease risk is greater. The fingerlings of Pangasius hypophthalmus are almost entirely produced by artificial rearing because the natural fingerling yield from the Mekong River has been reduced (Van Zalinge et al 2002).

The hypotheses that were tested in this experiment were that: (i) catfish would grow faster with better feed conversion when biochar or charcoal was added to the feed or to the water in which the fish were raised; and (ii) that water quality in the fish tanks would be improved by addition of charcoal or biochar.

Materials and methods

Location and duration

The experiment was conducted in the experimental farm of the Aquaculture Department, Faculty of Agriculture and Natural Resources, An Giang University, An Giang province, Vietnam. The duration of the study was 3 months from July to October 2014.

Experimental treatments and design

The treatments were:

BF: Biochar added to the fish feed
BW: Biochar added to the water
CF: Charcoal added to the  fish feed
CW: Charcoal added to the water
NBC: Control with no additives

The five treatments with 4 replications were arranged in a completely randomized design.

 Pangasius fry was bought at the hatchery farm in An Giang province and reared until 10 g of live weight (Photo 1). They were then transferred to 500 liter PVC tanks (Photo 2) at a stocking density of 35 fingerlings in each tank (Photo 3).

Photo 1. Fish were 10g at the beginning	Photo 2. Tanks used in the experiment	Photo 3. Tra fish in the tanks.

Feeding and management

Biochar was made by combusting rice husk in an updraft gasifier stove (Olivier 2010). Charcoal was bought from the Long Xuyen market. These additives were mixed with fish meal, wheat flour, maize and soybean meal (Table 1) and made into pellets of mm diameter.

The fish were fed to appetite (approximately 5% of LW/d), two times per day at 7:00 and 17:00h. The daily amounts of biochar or charcoal added to the water in BW and CW were based on the amounts fed in BF and CF. The fish on the NW treatments were fed the NBC diet. The uneaten feed and fish excreta in the tanks were removed by siphoning. Fresh water was added before feeding in the morning at the same time as adding the biochar and charcoal to the water. The water was exchanged twice weekly.

Measurements

The fish were weighed and measured (for length) at the beginning and end of the trial, and at 15day intervals during the experiment.

The following water parameters were measured (according to APHA 1995) every two weeks, in the morning before adding/exchanging water.:  pH, NO₂^-, TAN (total ammonia N), disolved oxygen, temperature and COD.

Chemical analysis

Feed offered was analyzed for dry matter DM, OM, ash, lipids and N according to the methods of AOAC (1990).

Phytoplankton and zooplankton densities were determined by the method of Coutteu (1996).

Statistical analysis

The data were analysed with the general linear model (GLM) option of the ANOVA program in the Minitab software (Minitab 2010). Two analyses were made:

(i) as a 2*2 factorial arrangement in which sources if variation were: additive (biochar or charcoal), medium (feed or water), interaction additive*medium  and error; and

(ii)  as a random block arrangement  in which the sources of variarion were: biochar in feed, charcoal in feed, no additive in feed and error.

Results and discussion

Water quality

The levels of pH and DO did not differ among treatments (Tables 2 and 3) and were within the suitable range for the growth of fish (Boyd 1990). By contrast, the values for total ammonia N, NO₂^-, PO₄^3-and COD were lower when biochar or charcoal was included in the feed (Table 2; Figures 1a-d). Similar results were reported by Jahan et al (2014) for total ammonia N when bamboo charcoal was added to the feed of P. hypophthalmus.  Adding biochar or charcoal to the tank water increased the levels of  NO₂ , TAN, PO₄^3- and COD (Table 3; Figures 2a-d).  Nitrite levels in our study were especially low (Tables 2 and 3) but this could partially be related to the use of plastic tanks, as sources of nitrite are typically from reduction of nitrate by bacteria in anoxic mud and water as in natural ponds (Boyd 1982).

Figure 1a. Effect on NO2 in the tank water of adding biochar or charcoal in fhe feed	Figure 1b. Effect on TAN in the tank water of adding biochar or charcoal in fhe feed	Figure 1c. Effect on PO4 in the tank water of adding biochar or charcoal in fhe feed	Figure 1d. Effect on COD in the tank water of adding biochar or charcoal in fhe feed

Figure 2a. Effect on NO2 in the tank water of adding biochar or charcoal to the feed or the water	Figure 2b. Effect on TAN in the tank water of adding biochar or charcoal to the feed or the water	Figure 2c. Effect on PO4 in the tank water of adding biochar or charcoal to the feed or the water	Figure 2d. Effect on COD in the tank water of adding biochar or charcoal to the feed or the water

Feed intake, growth, conversion and survival

Growth rates were increased 36% by adding biochar to the feed and by 44% with charcoal (Table 4; Figure 3). There were no benefits from adding either biochar or charcoal to the water (Table 5). In fact, it appeared that adding biochar or charcoal to the water had a negative effect on feed intake (Figure 2) and, as a result of reduced feed intake,  growth rates were also reduced (Table 5). Similar improvements in growth rate of P. hypophthalmus by adding bamboo charcoal to the feed were reported by Jahan et al (2014), with the optimum level at 1% of the feed (Figure 4).

The ratio of weight to length in the fish at the end of the experiment was 25% greater when biochar or charcoal were added to the feed, indicating an enhanced flesh to bone  ratio due to the additives.

Survival rates were high on all treatments with a slight indication (p=0.24) of benefits from biochar and charcoal in the feed compared with none (Table 4). There was a negative effect (p = 0.027) on survival from adding biochar or charcoal to the water (Table 5).

The lack of effect of biochar and charcoal on fish growth when these substances were added to the water could be due to the lower density of these substances relative to water. Thus when added to  the water in the tanks they first floated on the surface then sank to the bottom. In such a situation it is unlikely that the added particles would be consumed by the fish, and more likely would inhibit to some extent the consumption of the supplementary feed, which could be the explanation for the lower feed intake when charcoal and biochar were added to the water compared with adding them to the feed (Figure 4).

Figure 3. Effect on weight gain of adding biochar (B) or charcoal (C) to the feed (F) or to the water (W) in the tank or no addition of either (NO)	Figure 4. Effect on feed intake of adding biochar or charcoal to the feed or to the water in the tank

Figure 5. Effect of increasing proportions of bamboo charcoal in the diet on growth of P. hypophthalmus (Jahan et al 2014)

Densities of phytoplankton were greater in all treatments with biochar and charcoal, with highest values when these were added to the water (Table 6; Figure 6).  There were similar tendencies for density of zooplankton (Figure 7). However, these differences were not related to fish growth rates or feed conversion.

Figure 6. Densities of phytoplankton in the water	Figure 7. Densities of zooplankton in the water

Fish undoubtedly harbour a wide range of microorganisms in their digestive tract where they influence a broad range of host biological processes and play critical roles in development and health including digestive processes (Romero et al 2014; Ringo et al 2014).The majority of these processes appear to apply across invertebrates . The role of the microbiota in digestive tract of fish appears to be  similar to those described for human and animals in general (Romero et al 2014). In fact the gut microbiota effects a number of other reactions in the animal including the control of digestion and metabolism and also interactions with the immune system. In the human  gut, microbiota are so influential  that animals are being treated as super–organisms (Eberl 2010) as the numbers of  microbial cells in the microbiota equals or exceeds those of the total animal cell numbers (Eber 2010). Most microbes in the gut are present as microbial biofilms (Bevins and Salzman 2011 ) that adhere to the solid feed particles or the epithelial cell wall of the gut. Providing feed characteristics that increase the surface area of solid materials in the gut lumen, potentially allows a greater surface area for biofilm formation which in turn increases the rate of chemical processes or makes them more efficient (Schink and Thauer 1988; see also Leng 2014).

Biochar has an enormous surface area to weight depending on the method of production (Lehmann and Joseph 2009) and the boost in production seen in the cat fish that were  given biochar  in the feed pellet could be owing to this factor which is a similar hypothesis to that put forward for the  benefits of biochar in  ruminants when biochar was added to their feed (Leng et al 2014).  The implication is that the provision of biochar increases the rate and possibly the extent of feed digestion by providing habitat for the gut microbiota which then become more efficient  and the animals may increase feed intake, possibly feed digested and the efficiency of feed utilisation. 

Conclusions

• Growth rates of catfish were increased 36% by adding biochar to the feed and by 44% with charcoal.
  
  
• There were no benefits from adding either biochar or charcoal to the water. In contrast, adding charcoal to the water had a negative effect on feed intake and on growth rate.
  
  
• Survival rate was reduced from 100 to 96.4% when biochar or charcoal were added to the water.
  
  
• The ratio of weight to length in the fish at the end of the experiment was 25% greater when biochar or charcoal were added to the feed.
  
  
• The additional surfaces provided by< charcoal or biochar provide additional habitat for biofilm attachment and increase the rate of solubilisation of solid feed materials through more efficient syntrophic microbiota in the digestive tract of the fish. This could be a major factor contributing to the improved growth rates recorded with biochar and charcoal added to the diet.

References

AOAC 1990 In Helrick (Ed.), Official Methods of analysis. Association of Official Analytical Chemists 15^th edition. Arlington. pp 1298 pp.

APHA 1995 Standard Methods for the Examination of Water and Waste Water. 18th Edn., American Public Health Association, Washington, DC, USA.

Bevins C L and Salzman N H 2011 The Potter's Wheel: The host's role in sculpting its microbiota. Cellular and Molecular Life Sciences. 2 ; 68(22): 3675–3685.

Boyd C E 1982 Water quality management for pond fish culture. Elsevier, Amsterdam.

Boyd C E 1990 Water quality in ponds for aquaculture. Alabama agriculture experiment station, Auburn University. Birmingham Publishing Co. Birmingham, Alabama. First printing 5M, December 1990.

Chau Thi Da, Amararatne Yakupitiyage, Wenresti G. Gallardo, Hakan Berg and Yang Yi 2007 Environmental Impacts from Feeds Used in Aquaculture Systems in the Vicinity of the Mekong River, Vietnam

Coutteau P 1996 Micro-algae. In: Manual on the production and use of live food for aquaculture. Patrick Lavens and Patrick Sorgeloos (Eds). Published by Food and Agriculture Organization of the United Nations: 9-59.

Eberl G 2010 A new vision of immunity: homeostasis of the super-organism. Mucosa Immunology.3, 450–460

Jahan R, Abdul Quaiyum M, Nusrat Jahan, Akhter T and Sadiqul Islam M 2014 Dietary added bamnoo charcoal can evoke Pangasianodon growth and can reduce ammonia from culture medium. International journal Fisheries and Aquaculture. Volume 6 (7) p.87-93. ISSN:2006-9839.

Lehmann J and Joseph S (Editors) 2009 Biochar for EnvironmentalManagement; Science and Technology. Earthscan, London, EC1N 8XA, UK, Sterling,VA 20166-2012, USA

Leng R A, Preston T R and Inthapanya S 2012 Biochar reduces enteric methane and improves growth and feed conversion in local “Yellow” cattle fed cassava root chips and fresh cassava foliage. Livestock Research for Rural Development. Volume 24, Article #199. http://www.lrrd.org/lrrd24/11/leng24199.htm

Leng R A 2014 Interactions between microbial consortia in biofilms: a paradigm shift in rumen microbial ecology and enteric methane mitigation. CSIRO PUBLISHING Animal Production Science, 2014, 54, 519–543 Perspectives on Animal Biosciences http://dx.doi.org/10.1071/AN13381

Minitab 2010 Minitab User's guide. Data analysis and quality tools. Release 16.1 for Windows. Minitab Inc., Pennsylvania, USA.

Olivier P 2010 The small-scale production of food, fuel. feed and fertilizer from recycled wastes. Live stock production, climate change and resource depletion. International Conference, Pakse, Laoshttp://mekarn.org/workshops/pakse/html/olivier.docx

Preston T R 2015 The role of biochar in farming systems producing food and energy from biomass. In: Geotherapy: innovative methods of soil fertility restoration, carbon sequestration, and reversing CO2 increase. Edited by Thomas J. Goreau, Ronal W. Larson, Joanna Campe. Boca Raton : CRC Press, [2015]

Ringo E and sixteen other authors 2016 Effect of dietary components on the gut microbiota of acuatic animals. A never endinng story? Aquaculture nutrition. November. John Wiley & Sons, Ltd

Romero J, Ringø E and Merrifield D J 2014 The Gut Microbiota of Fish Aquaculture Nutrition: Gut Health, Probiotics and Prebiotics. First Edition. Edited by Daniel Merrifield and Einar Ringø. Published 2014 by John Wiley & Sons, Ltd.

Schink B and Thauer R K 1988 Energetics of syntrophic methane formation and the influence of aggregation. In ‘Granular anaerobic sludge: microbiology and technology’. (Eds G Lettinga, AJB Zehnder, JTC Grotenhuis, LW Hulshoff-Pol) pp. 5–17. (Pudoc: Wageningen, The Netherlands)

Van Zalinge Nicolaas, Lying, Sophia , Ngor, Peng Bun, Heng, Kong and Jørgensen J V 2002 Status of the Mekong Pangasianodon hypophthalmus resources, with special reference to the stock shared between Cambodia and Viet Nam. MRC Technical Paper No. 1, Mekong River Commission, Phnom Penh. p.29. ISSN: 1683-1489

Received 25 December 2015; Accepted 17 April 2016; Published 1 May 2016

Go to top