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Title Sticks in the mud; Periphyton-based aquaculture   Themes Aquaculture, fish, fish culture, fish production, fishery research, food security, income generation   Introducing the practice Periphyton are the tiny organisms that live on the surfaces of objects under water. Periphyton-based practices have developed independently and are used to catch fish in open waters in various parts of the world. In West Africa the practice is known as Acadja, in Bangladesh it is called Katha, and in Cambodia Samarah. The present research project, which was conducted in Mymensingh, Bangladesh, has applied this technique to the farming of fish in ponds. The people of Bangladesh are resource-poor. Most people live from agriculture, of which fish culture is an important component. Most households have multi-purpose ponds that are used, among other things, for bathing and sanitation, for irrigating fields and gardens, and for growing fish. The fish are consumed by the families as well as being sold. The Acadja practice was first described by Welcome in 1972. The present periphyton project was conducted between October 1997 and April 2001. Bamboo stems and branches, jute sticks, the remains of sugarcane stalks, and/or tree branches are all used as substrate. The various stalks are inserted vertically into the pond bottom, where they are colonized by the plankton, microbes, invertebrates and other organisms that make up periphyton. The best result is achieved if the surface area of the substrate is equal to approximately 50-100% of the pond’s surface area. Ordinarily, fertilization is recommended for ponds with low productivity: for example the fortnightly application per ha of 4,500 kg decomposed cow dung, 100 kg urea and 100 kg Triple Super Phosphate (TSP). Ponds with high productivity need reduced rate of fertilization. Under the project, ponds were stocked with three major species of Indian carp: 4000 Catla catla, 6000 Labeo rohita and 1500 Labeo calbasu per hectare of pond. Even without feed, ponds with substrate produced twice as much fish as ponds without it. In the project’s experimental ponds, where bamboo was used as substrate and no extra feed was given, fish production reached 2,305 kg per ha within 90 days. The technology seems to hold promise for the farming of any herbivorous fish which is capable of harvesting periphyton from substrates.   Contents and approach Traditional Acadja, Katha,and Samarah are still widely used. The periphyton research reported here was done at a field station. Farmers are also using this technique in ponds, but they cannot yet say exactly how much of their increased production is due to a periphyton substrate. More on-farm trials are underway, however. Thus far, it has been found that: ·           The farmers believe that shaola (periphyton) can grow on substrate, and that this can be used as fish feed. ·           Substrates are available within their farming systems. ·           Substrates protect the farmers’ ponds from fish poachers, since it is difficult to use nets in ponds with substrate. The probability that the technology will be adopted is therefore very high; it could affect all rural areas throughout Bangladesh. Origin of the practice The practice originated in the community. The idea of using the periphyton technique in ponds came from researchers, but farmers grasped the idea quickly because the technique is traditionally used to attract fish in open waters. In rivers, for example, fishermen install bushy substrates where fish gather to breed, feed or shelter. After a time the fishermen catch the fish. Although the technique is practised mainly by households that farm fish, the whole community benefits because total fish production increases. At the same time, the pressure on over-fished natural waters decreases. The practice was first tried out in experimental ponds and subsequently disseminated to farmers by NGOs. The aim of the practice is to increase fish production without increasing the level of nutrient inputs. The only additional input needed are sticks or branches, which the farmers can provide themselves. In traditional ponds, phytoplankton is the basic fuel of the food chain and the most important source of energy. It does not generally meet all the energy demands of most herbivorous fish, however. They need supplemental feed or larger food that can be harvested more efficiently, such as benthic algae, detritus or aquatic plants of a higher order. Benthic algae rarely grows on the bottom of ponds because there is not enough light. But it will grow on hard substrates, or mats, installed in ponds, as will a film of bacteria and colonies of invertebrates. Fish can graze on these concentrated forms of food more efficiently than they are able to filter planktonic algae. Periphyton mats also improve water quality.   The role of indigenous knowledge The practice originated from indigenous knowledge regarding devices to attract fish. The farmers therefore find it easy to understand and apply the technology. What the project did was to test whether the traditional technique could be used under pond conditions to increase production. The practice can improve the socio-economic status of rural people by generating income and employment, and increasing fish consumption. The practice also has some weaknesses, however. Because substrates make it difficult to harvest only some of a pond’s fish, the practice can interfere with a household’s regular consumption of fish. If the practice is applied on a large scale, the need for substrates competes with other household purposes for which branches and sticks are used, such as cooking. Bamboo stems would be an option, but they are expensive. Nevertheless, this technology shows great promise since the increase in fish production is so large. Transfer of knowledge Although most members of the community already know how to use substrates to increase fish production in ponds, several NGOs—namely CARE-Bangladesh—are disseminating this knowledge to the community. Information about the practice has also been widely published in scientific journals, magazines and newspapers, and presented at workshops and conferences.   Achievements and results The periphyton-based aquaculture used in ponds in Bangladesh is considered to be a Best Practice for the following reasons: ·           Because the local people are acquainted with the practice in another context, they apply it easily to their aquaculture ponds. ·           It is a simple technology requiring only simple, cheap and readily available inputs. Anyone can use it; specialists are not needed. ·           The intensity of the practice can be adjusted to the availability of resources. If the technique were applied nationwide it could increase production considerably without any addition of nutrients. No other technique offers so much potential for so little investment. ·           Because productivity is increased without increasing nutrient inputs, higher nutrient efficiency is achieved. This, and the fact that the system produces less waste, means that the farming system has become more sustainable. ·           The practice reduces poaching. ·           Aquaculture is practised throughout Bangladesh, and wherever aquaculture is practised, periphyton-based aquaculture can be practised. Sustainability and cost-effectiveness The materials used for the substrate are used in local households for other purposes as well. This means that aquaculture must compete with other activities for resources. This is not a constraint, however, since the increased production of fish more than compensates for the effort involved in finding alternative materials. Certain agricultural by-products could gain in importance as a result of the periphyton technology. One such example is jute stick, the by-product of jute fibre. Once called ‘the golden fibre of Bangladesh’, jute stick lost the battle with synthetic fibres two decades ago. If jute stick is used as substrate, it could regain importance as a major resource in aquaculture. Another potential problem is that the increase in fish production through this technology could play havoc with fish prices. This is unlikely, however, since the demand for fish in Bangladesh is very great and continues to grow at least as fast as the rapidly growing population. The practice is very cost-effective. More than half of the cost of all input is eliminated because it is no longer necessary to add feed to the ponds. Substrate materials are relatively cheaper. Most farmers can even supply them themselves from their own farms. All farmers know how ‘brush parks’ collect periphyton, which means they have the knowledge they need. The substrate can be produced within the local farming systems, with farmers using their own labour and resources. The most important strength of this practice is its flexibility. It is not a fixed technology, but can be adapted to the needs, capacities and resources of the users. The purpose for which it is applied can also vary: it can generate income or provide nutrition as required. The only disadvantage of the practice is that it becomes impractical to harvest only part of a fish crop since all of the substrate must be removed before any fish can be extracted. A restriction of the practice is that not all types of substrate can be used. Some types of material cause the water quality to deteriorate. More research is needed on this point. Development potential Biodegradable materials can be used as substrate. This has at least two advantages: ·           The substrate has broken down by the time the harvest takes place, so there is no need for its removal. Partial harvests also become possible. ·           Biodegradable substrates can add additional nutrients to the system, giving an additional boost to production. Often these nutrients would otherwise be lost to the agricultural system. Local people possess a lot of indigenous knowledge about polyculture systems—systems that exploit the ecosystem of the pond more fully by raising a number of fish species at the same time. Periphyton technology blends perfectly with polyculture systems. In on-station trials so far, the highest production levels have been obtained by combining periphyton and polyculture systems. Besides improving productivity and thus food availability, the presence of periphyton has a positive effect on: ·           Water quality. ·           The health of the system and the animals in it. Preliminary research indicates that the presence of micro-organisms on substrates improves the health of the culture stocks, resulting in less mortality or losses, and overall healthier animals. The subjects mentioned above point in the direction of further research on such topics as the development of periphyton-based bio-filters, and the application of vaccines through biofilms in aquatic systems. These techniques would be applicable in both rural and industrial aquaculture.   Source of inspiration It would be no problem at all to transfer the practice to another group, culture, land-use system, etc. Substrate can be added to any type of outdoor pond system. Basic indigenous knowledge regarding the use of Acadjas or ‘brush parks’ might be lacking in some regions, however. The practice has been replicated in Mangalore, India, by researchers and fish farmers. If you think that this case could be useful in a different context than the one described here, please get in touch first with the contact person listed below (Administrative data). Intellectual property rights could be an issue.   Additional remarks and information ·           Azim, M.E., Wahab, M.A., van Dam, A.A., Beveridge, M.C.M., Verdegem, M.C.J., (2001). ‘The potential of periphyton-based culture of two Indian major carps, rohu Labeo rohita (Hamilton) and gonia Labeo gonius (Linnaeus)’. In: ‘Aquac. Res.’ 32, 209-216. ·           Azim, M.E., Wahab, M.A., van Dam, A.A., Beveridge, M.C.M., Milstein, A., Verdegem, M.C.J. (2001). ‘Optimization of fertilization rates for maximizing periphyton growth on artificial substrates and implications for periphyton-based aquaculture’. In: ‘Aquac. Res.’ 32, 749-760. ·           Azim, M.E., Wahab, M.A., van Dam, A.A., Beveridge, M.C.M., Huisman, E.A., Verdegem, M.C.J., (2001). ‘Optimization of stocking ratios of two Indian major carps, rohu (Labeo rohita Ham.) and catla (Catla catla Ham.) in periphyton-based aquaculture systems’. In: ‘Aquaculture’ 203, 33-49. ·           Azim, M.E., Verdegem, M.C.J., Wahab, M.A., van Dam, A.A., Beveridge, M.C.M., (2001). ‘Periphyton boosts production in pond aquaculture systems’. In: ‘World Aquacult.’ 32(4), 57-61. ·           Azim, M.E., Wahab, M.A., Verdegem, M.C.J., van Dam, A.A., van Rooij, J.M., Beveridge, M.C.M. ‘The effects of artificial substrates on freshwater pond productivity and water quality and the implications for periphyton-based aquaculture’. In: ‘Aquat. Living Resour’ 15(4), 231-241. ·           Azim, M.E., Verdegem, M.C.J., Rahman, M.M., Wahab, M.A., van Dam, A.A., Beveridge, M.C.M. ‘Evaluation of polyculture of Indian major carps in periphyton-based ponds’. In: ‘Aquaculture’ 213, 131-149. ·           Azim, M.E., Verdegem, M.C.J., Khatoon, H., Wahab, M.A., van Dam, A.A., Beveridge, M.C.M. ‘A comparison of fertilization, feeding and three periphyton substrates for increasing fish production in freshwater pond aquaculture in Bangladesh’. In: ‘Aquaculture’ 212, 231-247. ·           Azim, M.E., (2001). ‘Sticks in mud that work’. In: ‘Spore’ Vol. 95 (October issue). pp. 9. ·           Azim, M.E., (2002). ‘Fish farming can help fight poverty in Bangladesh’. Wb Vol. 2 (January issue). pp. 4. ·           Azim, M.E., (2002). ‘Periphyton-based aquaculture’. In: ‘the Bangladesh Observer’ on 22 March. ·           Keshavanath, P., Wahab, M.A., (2001). ‘Periphyton-based aquaculture and its potential in rural development’. Summary of an EC INCO-DC funded workshop. January 29-31, 2001, Ahsania Mission, Dhaka, Bangladesh. Published by Asian Fisheries Society, Indian Branch. ·           Verdegem, M.C.J., Azim, M.E., (2001). ‘Periphyton-based aquaculture: a novel fish culture technology’. In: ‘EC Fisheries Cooperation Bulletin’ 14(1-4): 37-40. ·           Wahab, M.A., Azim, M.E., Ali, M.H., Beveridge, M.C.M., Khan, S., (1999). ‘The potential of periphyton-based culture of the native major carp, kalbaush (Labeo calbasu Hamilton)’. In: ‘Aquac. Res.’ 30, 409-419. ·           Wahab, M.A., Azim, M.E., Verdegem, M.C.J., van Dam, A.A., Beveridge, M.C.M., (2001). ‘Periphyton-based Aquaculture: Potentials and Constraints’. In: Shankar, K.M., Mohan, C.V. (eds) ‘Potential of Artificial Substrate Based Microbial Biofilm in Aquaculture’. National Workshop Manual. UNESCO sponsored workshop held on 15-16 October 2001, Mangalore, India. pp. 45-59.   Administrative data Organization involved Faculty of Fisheries (Dr M.A. Wahab) Bangladesh Agricultural University, Mymensingh, Bangladesh Tel. number: +880 91 54927 Fax number: +880 91 55810 E-mail: wahabma@bdonline.com   Contact persons Dr M.E. Azim E-mail: ekram.azim@wur.nl   Dr M.C.J. Verdegem E-mail: marc.verdegem@wur.nl   Fish Culture and Fisheries Group P.O. Box 338, 6700 AH Wageningen, The Netherlands Tel.: +31 317 485157 (Azim), or -484584 (Verdegem) Fax: +31 317 483937   Other partner(s) involved in the practice ·           Institute of Aquaculture, University of Stirling, FK9 4LA Scotland, UK ·           Fish Culture and Fisheries Group, P.O.Box 338, 6700 AH Wageningen, Wageningen University, The Netherlands ·           College of Fisheries, P.B. 527, Mangalore 575-002, Karnataka, India   Funding Total budget: 450,000 US Dollars. Period to which the budget applies: October 1997- April 2001. EC INCO-DC programme.   Person(s) who have described this Best Practice Dr M.E. Azim and Dr M.C.J. Verdegem (see address above)

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