Managing Aquaculture Problems

Transcription

1 Managing Aquaculture Problems with Chemical-Free Water Treatment Solutions July 2006 Copyright 2006 SIF Technologies Pte Ltd, Singapore. All rights reserved. No part of this paper may be reproduced in any manner or medium, whether wholly or in part without the written permission of SIF Technologies Pte Ltd.

2 Table of Contents Global Aquaculture Market 2 Aquaculture in Singapore 2 Challenges from Regional Competition 3 Problems in Aquaculture 5 The Solution: DPA System 7 Overall Effect of DPA System on Aquaculture 9 Business Benefits 14 SIF Technologies DPA System 17 References 18 Abstract The global aquaculture market has continued to expand over the last few decades and in particular, Asian countries have dominated the global market for ornamental fish. Singapore is termed the Ornamental Fish Capital of the World as it is the leading exporter of ornamental fish in the world. However, Singapore faces stiffer competition from regional countries which have taken initiatives to foster the growth of the aquaculture industry in their home economies. To maintain Singapore s leading position, Singapore has also embarked on various plans, such as setting up the Ornamental Fish Business Cluster. There are problems in aquaculture operations, such as aquaculture wastes and effluents and chemical pollution. To meet these challenges, there is a need to increase the competitiveness and efficiency of the aquaculture industry. The solution is a chemical free technology that helps aquaculturists manage the quality of water. A pilot study was conducted using DPA system, in conjunction with Apollo Aquarium, a leading exporter and breeder of ornamental fish in Singapore. Application of the DPA system can result in substantial economic benefits, such as less reliance on chemicals, faster turnover and fall in usage of water. 1

3 Global Aquaculture Market The global aquaculture sector has continued to grow rapidly at an average rate of 8.9 % since In 2002, the total aquaculture production is reported to be worth US 60.0 billion. 1 In particular, the world trade in ornamental fish is worth more than US$4.5 billion with an annual growth rate of 8%. Asian countries are the dominant players accounting for a significant share of 68%. Over the last two decades, the value of world ornamental fish imports has risen significantly from US$50 million to US$250 million. The main importers of ornamental fish are the United States (25%), Japan (18%) and Europe, particularly Germany (9%), France (8%) and the United Kingdom (7%). 2 Singapore is the largest exporter of ornamental fish in the world To strengthen Singapore s leading position in the ornamental fish industry, the Ornamental Fish Business Cluster was formed in 2003 Aquaculture in Singapore Ornamental Fish Capital of the World The aquaculture industry in Singapore consists of mainly foodfish farming and ornamental fish farming. The consumption of fish in Singapore is estimated to be 100, 000 tonnes per year and about 5% of it is accounted for by local foodfish aquaculture. 3 However, Singapore is the largest exporter of ornamental fish in the world and is known as the ornamental fish capital of the world. In 2002, about 110 million pieces of ornamental fish were produced in Singapore and this accounted for 44% of the fish exported from Singapore. Singapore also exported 230 million pieces of ornamental fish to more than 70 countries. Considering the numbers of species and varities, Singapore transacts about half of the 1,000 species and varities sold globally. 4 Latest Developments There are various initiatives undertaken by the Agri-Food and Veterinary Authority of Singapore (AVA) to strengthen and maintain Singapore s position in this industry. In order to forge closer collaboration between AVA and the exporters and traders, the Ornamental Fish Business Cluster was formed in Dr Kenny Yap of Qian Hu Cooperation is presently the Chairperson of the Cluster on a 3-year term. Other committee members consists of representatives from IE Singapore, EDB, SPRING Singapore, associations (Exporters and Breeding) in Singapore and private companies with core businesses related to the activities of the Cluster. On the other hand, Swee Chioh Aquaculture Holding Pte Ltd is working closely with Marine Aquaculture 1 World Review of Fisheries and Aquaculture 2004, The State of World Fisheries and Aquaculture (SOFIA). Available: 2 Ornamental Fish Business Cluster (OFC) [On-line]. Available: 3 Agri-Food and Veterinary Authority of Singapore (AVA) Aquaculture [Online]. Available: 4 Ornamental Fish Business Cluster (OFC) [On-line]. Available: 2

4 Centre (MAC) of AVA to research on fish spawning and culture techniques of different foodfish species. MAC provides technical advice and support to those involved in the Singapore aquaculture industry. Malaysia is aiming to produce 800 million ornamental fish by the year Challenges from Regional Competition Malaysia Singapore is facing increasing competition from regional players. Malaysia has embarked on plans to become a prominent centre for the production of ornamental fish. It used to have only 18 fish farms but the number has grown to over 500 in recent years. The Department of Fisheries is embarking on various initiatives and setting up the institutional framework to encourage the growth of aquaculture, such as providing flexible credit facilities and investment tax allowance for ornamental fish farming activities. In 2004, Malaysia produced 456 million ornamental fish of which 95 per cent were exported. Under the 3rd National Agricultural Policy ( ) ornamental fish & aquatic plants are identified as the key to developing a dynamic fish sector. They are aiming to produce 800 million ornamental fishes by the year In the recent decade, the production and exports of ornamental fish has also increased steadily over the years. 5 (See Chart 1 and Chart 2) Chart 1: Ornamental Fish Exports Year Quantity (million pieces) Source Statistics: Department of Fisheries, Malaysia 5 Tay, Y. T. Malaysia aims to produce 800 million ornamental fish annually by 2010, Aquarama Magazine (May 2006) [Online]. Available: 3

5 Chart 2: Ornamental Fish Exports Year Value (Million USD) Source Statistics: Department of Fisheries, Malaysia A wholesale market and export centre for ornamental fish has been set up with a budget of 100 million Baht in Thailand Thailand The aquaculture sector is highly supported by the Thai government and various agencies and structures have been established to drive the growth of the industry. An ornamental fish research and development institute has been set up by the Department of Fisheries in Pathumthani province to provide technical assistance and training for the locals. With a budget of 100 million Baht, the wholesale market and export center for ornamental fish was built at Bangkhan in Pathumthani province in a vast area of one hundred rai. This allows ornamental fish to be collected from local breeders for export in a more efficient way. In addition, the Department of Fisheries organizes the annual Pramong Noam Kroa exhibition to promote local and international ornamental fish business. Challenges from the region can be met by tapping on advanced systems and techniques Meeting the Challenge The intensification of regional competition poses a substantial challenge for the aquaculture industry in Singapore and it cannot be ignored. With larger land mass and greater natural resources available, neighbouring countries such as Malaysia and Thailand have innate advantage over Singapore. Regional competitors can harness their resources by creating extensive aquaculture zones and increase their production and exports enormously. In order to meet the challenge, we can tap on modern technology to gain competitive advantage over our peers. Local players can collaborate with local firms and institutions to increase the efficiency of their farming techniques. Advanced systems and techniques can be utilized to help them increase their turnover and enhance the quality of their stocks. 4

6 Problems in Aquaculture The global aquaculture market has displayed immense growth potential. The proportion of seafood from wild fisheries is gradually decreasing while fish farming is becoming an increasing source of seafood for the world. However, existing aquaculture operations can pose significant problems for aquaculturalists as well as for the environment. Aquaculture wastes and effluents poses threats to fishes and other organisms living in the water and also form potential health risks to aquaculturalists. Aquaculture Wastes and Effluents Aquaculture wastes are often released directly into the water. This includes uneaten fish feed, fecal and excretes. However, the effects can differ depending on the type and location of the aquaculture system. A system open to natural waters will result in greater damage to the environment due to discharge of wastes but there will be relatively less damage in closed pond or tank systems which allow wastes to be disposed in a regulated manner. The amount of fish feed which becomes waste varies too. In cage systems, up to 15% of the dry-pelleted feed is not consumed by the fishes while the figure can be as high as 40% for trash fish (minced low value fish, fresh or frozen) 6. Furthermore, after the fish feed is consumed, it will be passed out as feces which add to aquaculture waste. Oxygen Depletion Due to Breaking Down of Fish Feed and Fecal causes Fish feed which is uneaten and fecal discharged from fishes are organic in nature and consist of a mixture of carbon-based compounds. Microorganisms use much of the oxygen in the water to break down the organic matter. This will stress the conditions of the aquatic system and kill the organisms and fishes which need oxygen to survive. Damage to Benthic Ecosystems The fish feed and fecal in aquaculture systems descends to the bottom and the waste built up at the bottom will enrich sediments, resulting in different forms of reactions. This will produce anaerobic (oxygen deficient) sediments. In serious cases, it may even lead to the release of toxic gases such as methane, hydrogen and sulfide. Eutrophication and Algae Blooms reduces level of dissolved oxygen The level of nutrients, such as nitrogen and phosphorus will also build up as they dissolve from feed, fecal wastes and fish excretes. As they accumulate and reach concentrated levels, hypernutrification occurs. This will stimulate the rapid growth of 6 Goldburg, R. & Triplett, T. (1997). Murky Waters: Environmental Effects of Aquaculture in the U.S., p. 35. The Environment Defense Fund. 5

7 algae by a process called eutrophication 7 which will cause damage to aquatic ecosystems. The growth and degradation of algae reduces the level of dissolved oxygen, thus threatening the survival to fish and other organisms. The use of chemicals in aquaculture has not mitigated problems but has caused further complications. The new solution is a chemical free technology Bacteria Pollution The water will be polluted with bacteria due to the fish sewage. A Canadian study showed that humans can be infected when we come into contact with raw farmed tilapia infected with the fish pathogen, Streptococcus. 8 This could pose potential health hazards to aquaculturists who have to handle the fishes regularly. Chemical Pollution In order to prevent diseases, inhibit algae growth, increase spawning rate and enhance the growth of fishes to acquire desired qualities, aquaculturists make use of a wide range of chemicals in their operations. However, this creates a host of problems too. Anti-Bacterial Drugs It is estimated that most of the antibiotics used on fishes are lost to the environment due to leeching from feces and uneaten fish feed and they end up being bounded to particles in the sediment, leading to chemical pollution in the aquatic systems. Through feeding on waste food and feces of treated fish, antibiotics can also accumulate in wild fish and shellfish, so it is possible that human beings consume residues of antibiotics from fish farms. Furthermore, the evolution of antibioticsresistant bacteria can be partly attributed to the use of antibiotics in aquaculture. Herbicides( Including Algicides ) A large number of chemicals are used to control algae growth and other aquatic plants but they are not too effective because aquaculturalists will usually continue to add fish feed to the aquatic system and create more nutrients, which will aid the growth of algae. In some fresh water aquaculture systems, the rapid growth of aquatic weeds can also cause the dangerous decline of dissolved oxygen levels in aquatic systems but spot treatments can only kill a portion of the weeds at a time. Moreover, if the herbicides become too concentrated, they could possibly cause harm to the animals which was not targeted by aquaculturalists in the first place. 7 Goldburg, R. & Triplett, T. (1997). Murky Waters: Environmental Effects of Aquaculture in the U.S., p. 37. The Environment Defense Fund. 8 Goldburg, R. & Triplett, T. (1997). Murky Waters: Environmental Effects of Aquaculture in the U.S., p. 40. The Environment Defense Fund. 6

8 Other Pesticides and Growth Hormones Pesticides are used as antifouling agents to deter the growth of fouling organisms but they are now known to reside in the organisms and the aquatic systems. This pollutes the environment and harms the farmed organisms. Fish hormone are generally used to enhance the growth of the fishes, encourage spawning and they are often used to obtain fishes with qualities which will be preferred by consumers Adverse Effects on Aquatic Life Aquaculture can cause a great deal of environmental problems as the water will be polluted by aquaculture waste. In a joint project by the Department of Fisheries (DOF) of Thailand and the Food and Agriculture Organization of The United Nations (FAO), a study was undertaken to investigate the performance of some water quality parameters and the role of certain water conditions as disease stressors. 9 Pathological examination showed that the dead fishes were seriously infected with harmful bacteria (aeromonas). The high levels of un-ionized ammonia and carbon dioxide and low levels of dissolved oxygen are the possible stressors or even the direct causes of the fishes death. Aquaculturalists have attempted to manage the quality of water by the use of various chemicals but this has created chemical pollution, causing a new chain of problems. As a result, valuable resources have to be expended as the water needs to be constantly replaced in order to maintain the quality required for aquaculture. The Solution: DPA System SIF Technologies DPA system is designed based on the principle of cavitation, which is a patented proprietary technology. It alters the density structure of water and breaks it down into micron level. As a result, it can manage the quality of the water used in aquaculture and help overcome the challenges faced by aquaculturalists. DPA System can help: Improve Total Dissolved Oxygen conditions Inhibit anaerobic bacterial growth Increase water solubility 9 Vijai Srisuwantach, Rangsarn Soungchomphan and Pathipath Sae-Eng, Water Quality Conditions As Disease Related Stressors In Clarias Pond Culture, Programme for the Development of Pond Management Techniques and Disease Control (DOF - UNDP/FAO THA/75/012), Thailand 7

9 Client Located at Seletar West Farmway, Apollo Aquarium is the leading importer, exporter and wholesaler of ornamental fish in Singapore. Their range of products includes more than 100 types of platies and exotic species such as electric blue crayfish and Clown Loach. Apollo also caries a wide variety of aquatic plants, including the highly sought after Standing Pot Plant. A controlled experiment has been carried out jointly with SIF Technologies to verify the positive effects of DPA system. Hypothesis and Objectives of Study The hypothesis of the study is that Exponential growth is expected to be observed on aquatic life as improved water conditions (treated water) would facilitate an ideal habitat for spawning and growth development. This would in turn reduce the mortality rate of fish. The specific objectives are to document differences in treated water quality in comparison to PUB water and the tangible effects of DPA treated water on Growth rate Spawning Rate Mortality rate Implementation The species used in the study are the Beta Splendens which is also known as the Short Tail Fighting Fish. One set of optical recording equipment was used to capture the evidential growth of the fishes. Measurements instruments, such as TDO (Total dissolved oxygen), TDS (Total dissolved solids) and ph (percentage of hydrogen) meters were used to measure the readings. The measurements were taken daily and recorded. At the same time, observations were made using a microscope and pictorial evidences have also been recorded to substantiate the findings. Water was circulated within a holding area using DPA system for at least 24 hours before usage. This allowed time for the water to acclimatize to the surrounding walls of the holding area and ensured ecological stability. From 1 batch of fingerlings, 2 sample sizes were taken. To ensure fairness, both samples started with the similar conditions: TDO (Total Dissolved Oxygen) count, ph monitoring and bacteria count (using APHA 9215D Standard Plate Count). These 2 samples sizes were then subjected to different treatment: one is placed in DPA treated water and the other in normal (untreated) water. 8

10 Project Parameters Parameters for Measuring Effects of DPA System on Quality of Water For the samples of treated and untreated water, the source, volume, temperature, environmental exposure, type of sand filters and amount of time for aging are kept the same. Parameters for Measuring Effects of DPA System on Fishes The control variable is the water used for rearing the fishes. To ensure the study was a controlled experiment, specific measures were taken to ensure that other than the control variable, all other conditions remain constant. Selection Both samples of fishes were hand picked by Mr Eric Ng for the experiment. This ensures that the process of selection is consistent. The fishes selected were approximately identical in shape and size on the first day of the experiment. Measurements The 2 samples of fishes were placed side by side, observed daily and measured 6 weeks after. Fish Feed The kind of feed, time of feed, frequency in feed and amount in feed were kept the same for both samples of fishes Others The amount of fishes, number of life bearers and egg bearers and the type of environmental exposure were the same for both samples of fishes Overall Effect of DPA System on Aquaculture Increase in Quality of Treated Water Inhibits Eutrophication and Algae Blooms The algae bloom deplete the water of oxygen and contributed to the low oxygen count. After using DPA system, it was observed that the algae growing in the water holding area has been inhibited. The holding area is now free from thick layers of algae. 9

11 Fig 1.1: The water conditions prior to the installation of DPA treatment system. Fig 1.1 Fig 1.2 and 1.3: Prior to the installation of DPA system, a thick layer of algae was found in the water holding area. Fig 1.2 Fig 1.3 Fig 1.4 and 1.5: The thick layer of algae was removed after the installation of DPA system Fig 1.4 Fig

12 Increase in Total Dissolved Oxygen (TDO) In water condition without DPA system, the Total Dissolved Oxygen (TDO) was 4.5 ppm but with the DPA system, the TDO of water increased to 7.4 ppm. There used to be fluctuating ph level in the various breeding ponds but after acquiring DPA system, the ph in the farm was stabilized at 6.8. These were observed in a period of 6 weeks. Test reports from Chemicals Testing and Calibration Laboratory also show consistent increase in the TDO from 3.21 ppm to 7.41 ppm in a period of 3 months Chart 3: This shows that the TDO level increased significantly from 4.5 ppm to 7.4 ppm in 6 weeks ppm Effects of DPA System in 6 Weeks With DPA System Without DPA System Total Dissolved Oxygen Total Dissolved Oxygen Chart 3 Chart 4: This shows that over an extended period of 3 months, the TDO level has increased steadily from 3.21 to 7.41 PPM Increase in TDO Over 3 Months Total Dissolved Oxygen (TDO) Chart 4 11

13 Surpasses PUB Drinking Water Standard Using drinking water standard set by PUB as a benchmark, test reports have also shown that DPA treated water have attained key indicators well accepted by PUB and even surpassed them. For example, the Total Dissolved Solids (TDS) standards set by PUB is below 500 ppm but independent test reports show that the TDS level of DPA treated water is consistently below 20 ppm. Moreover, the level of chloride set by PUB standards is less than 250 ppm but DPA treated water has consistently been less than 20 ppm. (See Appendix A) Increase Growth Rate After subjecting the water to DPA system, it has been found that the fishes in DPA treated water grew faster compared to the ones in untreated water. There has been an exponential growth for the fishes in DPA water. The fishes in both samples were not fed but the fishes in DPA water have displayed high energy levels. The fishes took a much shorter period to grow up to the same size. The fishes subjected to DPA water took 6 weeks to grow to an average size of 4.5 cm. On the other hand, the fishes in untreated water only grew to an average size of 2.5 cm. It will normally take 3 months for the fishes to grow up to a length of 4 cm and DPS system had accelerated the growth of the fishes. Fig 2: The fish on the left was reared in DPA treated water while the one on the right was in normal water It normally takes 3 months to grow to 4.5 cm but In DPA treated water, it took 6 Fig 2 weeks. 12

14 Increase Spawning Rate DPA system has been shown to have increased the spawning rate of the livestock by a substantial amount. It was reported by Apollo Aquarium that the spawning rate of Cherax, otherwise known as the Blue Lobster has risen by 200% in a period of 6 weeks. Reduce Mortality Rate Increase in TOD also led to the fall in mortality rate. In order to reduce mortality rates, vaccines or antibiotics are usually used in aquaculture to increase the fishes chances of survival. The use of DPA system has yielded positive benefits. Despite a reduction in the use of vaccines by 50%, Apollo Aquarium s export to overseas suffered near zero DOA (Death on Arrival). Further examination also indicates that DPA treated water has positive effects on the internal organs (i.e.) of fishes. The internal organs of a fish reflect its health condition. Red lines found on gills mean that the fish is in good health condition. On the other hand, black lines mean that the fish has sustained injuries or suffer damage to its gills due to lack of oxygen. Fig 3.1: Biopsy was conducted to show the effects of DPA treated water on the internal organs of a fish. Fig 3.1 A biopsy was conducted to show the effects of DPA treated water on the internal organs of a fish. This shows that the gills are in good condition. Next, a microscope was used to investigate the conditions of the gills in detail. Microscopic view shows that the gills of fish specimens. The area where oxygen is taken in is red and this indicates that the specimen was in good condition. On the other hand, for fishes which were not placed under the DPA system, the gills were turning black. This was an indication that fish was in poor health condition due to the lack of oxygen. 13

15 Fig 3.2: Microscopic view of fish in DPA treated water shows that the gills are in good condition. The area where oxygen is taken in is red in colour Fig 3.2 Fig 3.3: Microscopic view of fish in untreated water. The Gills are turning black, which is a sign that the fish is not healthy Fig 3.3 Business Benefits The DPA system can possibly generate greater cost savings, faster turnover and fetch higher market value for the livestock Greater Cost Savings Fall in Utilities bills DPA system can help aquaculturists reduce their usage of water. Aquaculturists usually have to use huge volumes of water in their operations as they have to maintain the quality of water at an acceptable level. However, use of DPA system allows aquaculturists to recycle water and reduce the frequency of replacing it. For example, Apollo Aquarium has seen a huge drop in the usage of PUB water in the farm as they can recycle their water. Previously, the amount of water used by Apollo usually ranges from 1500 Cu M to 2000 Cu M but within 6 months, the usage of water has dropped to less than 1000 Cu M and consistently remained at that level. 14

16 Chart 5: In 6 months, the water usage level has been reduced significantly to less than 1000 Cu M per month Water (Cu M) Decrease in Water Consumption over 6 months Jun Jul Aug Oct Nov Dec Month Water Consumption Chart 5 *Consumption for November was based on actual reading while the others were based on estimated reading Reduction in Chemical Usage DPA system s proprietary technology does not require the use of chemicals to manage aquaculture problems. Aquaculturists normally uses chemicals, such as vaccines and antibiotics to increase the resistance of their fishes and the usage of chemicals will translate to additional costs for them. However, DPA system s unique capability can help aquaculturists manage the quality of the water, thus lessening the reliance for vaccines. Apollo Aquarium estimated that they managed to reduce their vaccine use by 50%. This means there is a proportionate increase in the cost savings for chemical usage. Increase in Packing Density DPA system helps to increase the quality of water used for the delivery of fishes. In this way, aquaculturists can increase the amount of fishes being packed in the same volume of water. Previously, Apollo Aquarium was able to pack 1000 shrimps in their usual packaging. However, with the DPA system, they are able to pack 2000 shrimps into the same shipment, without causing any casualties. The packing density has increased by 100% and this decreases the frequency of freights, thus translating to savings in freight costs. 15

17 The treatment unit has not only been cost effective but has amounted to much cost savings within such a short period of time. (Appendix B) Quoted from customer Faster Turnover DPA system allows the turnover rate to increase. The Beta Splendens normally take about 3 months to grow to an average size of 4.5 cm but after using the DPA system, they took 6 weeks to grow to the same size. The turnover rate using DPA system treated water is 2 times that of using normal water. This could possibly shorten the whole cycle of rearing the fishes and bringing them to the market. As a result, aquaculturists can reap the returns from their investment in a shorter time. For example, if the fishes can be sold for $5000 after 3 months, the faster turnover rate will allow aquaculturists to sell the fishes for 2 times in 3 months and possibly double the revenue. Greater Market Value DPA system can possibly help to increase the market value of the fishes reared by aquaculturists. This is due to the better quality of water managed by the DPA system. There was a significant increase in total dissolved oxygen from 4.5 ppm to 7.4 ppm in the treated water. The fluctuating ph (percentage of Hydrogen) has also stabilized with the use of DPA system. The ph level has consistently remained between 6.8 to 7.2 which has created a conducive environment for fishes to thrive in. As a result, the fishes are in better health condition. Previously, Aquaculturists who export fishes to different countries have to take special precautions so that DOA can be minimized. Due to the favourable conditions, the fishes are more resistant and they suffered zero DOA (Death On Arrival) when exported overseas. The spawning rate of Cherax (Blue Lobster) had increased by 200% in 6 weeks. Furthermore, Fingerlings (Beta Splendens, otherwise known as short fighting fish) which are placed in DPA system treated water are three times the size compared to the fish in untreated water. The fishes produced with the DPA system are of higher quality and in better condition, so they are likely to fetch a higher market price. 16

18 SIF Technologies DPA System SIF Technologies DPA system offers a significant economic and environmental advantage over conventional methods. Applying it to aquaculture can help aquaculturists improve the quality of water which is hugely affected by aquaculture wastes and effluents. Concurrently, it reduces the need for chemicals, thus mitigating the problem of chemical pollution. The pilot study conducted with Apollo Aquarium has shown tangible results. The quality of water has displayed marked improvement over a period of continual usage. The spawning rate and growth of the livestock has increased and the mortality rate has been reduced. These effects can possibly lead to positive impacts on the business, such as faster turnover, higher cost savings and greater market value for its produce. Thus, the DPA system can be viewed as viable and cost effective solution for improving the competitiveness and efficiency of aquaculturists. However, it must be recognized that The above mentioned results are strictly confined to this project and results may vary from farm to farm as there are other factors that have not been taken into account, such as the total dissolved solids in the water, existing contaminants, water conditions etc. Documented by: Charles Tewer Project Engineer SIF Technologies Pte Ltd Edited by: Wee Gee Shing Marketing Communications Executive SIF Technologies Pte Ltd 17

19 References World Review of Fisheries and Aquaculture The State of World Fisheries and Aquaculture (SOFIA). Available: Ornamental Fish Business Cluster (OFC) [On-line]. Available: Agri-Food and Veterinary Authority of Singapore (AVA) Aquaculture [Online]. Available: Tay, Y. T. Malaysia aims to produce 800 million ornamental fish annually by 2010, Aquarama Magazine (May 2006) [Online]. Available: Goldburg, R. & Triplett, T. (1997). Murky Waters: Environmental Effects of Aquaculture in the U.S., p. 37. The Environment Defense Fund. Available: Vijai Srisuwantach, Rangsarn Soungchomphan and Pathipath Sae-Eng, Water Quality Conditions As Disease Related Stressors In Clarias Pond Culture, Programme for the Development of Pond Management Techniques and Disease Control (DOF - UNDP/FAO THA/75/012), Thailand. Available: 18

20 Appendix A 19

21 Appendix B 20