Traditional aquaculture is integrated with other human activity systems as these provided the only available sources of nutritional inputs for farmed aquatic organisms in the past. However, farmers are intensifying to earn more money through introduction of new or improved higher value species, sometimes raised in monoculture, and increasing integration with feedlot livestock and/or using pelleted feed.
VAC is an acronym for the Vietnamese words vuon (garden), ao (pond) and chuong (livestock quarters) on crop-dominated farms. Traditional integrated small-scale aquaculture (SSA) in the Red River Delta has provided food and some income for generations as most farming households have small ponds located near the house dug for soil for use as fill to raise the level of the land for the homestead and surrounding garden. Ponds are traditionally multipurpose: domestic water; watering vegetables; cultivation of floating aquatic plants for feeding pigs; and harvesting wild fish. Farmers traditionally raise a polyculture of common carp (Cyprinus carpio), Chinese carps (grass carp, Ctenopharyngodon idella and silver carp, Hypophthalmichthys molitrix) and Indian major carps (mrigal, Cirrhinus mrigala and rohu, Labeo rohita) integrated with livestock (pigs and poultry) and crops (fruit and vegetables). The three main traditional pond nutritional inputs are rice bran, grass and pig manure with pond mud periodically removed to fertilise dike crops.
Research Institute for Aquaculture No. 1 (RIA No. 1) refers to the intensifi cation of VAC as ‘improved VAC’. The relatively recent introduction of agro-industrially manufactured pelleted feed which is the main factor in the rapid increase in aquaculture production I define as ‘modern’ aquaculture. This intensification requires considerably more investment than use of on-farm or local resources such as wastewater but the farm profits are much higher through increased production which is the major driving factor. Intensification is especially taking place in areas near cities with a ready market.
Some fish farms are now rather large and may cover several hectares with all the rice fields being converted into ponds and pond dikes upon which vegetables and fruit trees are planted and /or livestock are housed. Viet Nam has a policy of agricultural diversification because rice farming does not provide an adequate household income. Since 1991 the government policy has allowed conversion of poor quality land on which agriculture was not profitable to be converted into fish ponds. Increase in farm size is now possible due to the emergence of a land market with rural households leasing land in or out. Land rental markets allow more productive farming households to gain access to land and increase output; and allow other households to pursue non-farm income opportunities in a rapidly expanding economy.
Two recent visits to Viet Nam in April and October 2010 provided an opportunity to witness the rapidly changing face of aquaculture in peri-urban Hanoi and an adjacent province, Hai Duong: the fi eld trip to Hai Duong province followed the FAO Expert Workshop on Enhancing the Contribution of Small-Scale Aquaculture (SSA) to Food Security, Poverty Alleviation and Socio-Economic Development, 21-24 April 2010 in Hanoi for which I was commissioned to prepare background papers on definitions, characterisation and numbers of small-scale aquaculture; and their contribution to economic growth, poverty alleviation and rural development; and reviewing the RIA No.1 component of the EU-funded Asia-Link aquaculture education project in October 2010. I observed improved VAC in Hai Duong Province in April and both improved VAC and declining wastewater-fed aquaculture in Thanh Tri District of Hanoi in April and October.
Improved VAC in Hai Duong Province
Two farms were visited in a previously low-lying area of the province that used to farm mainly rice but have now been converted into fi sh farms. The farmers used to have such low yields of rice that they could not even pay the local commune tax because the rice fields flooded every year. About 20 years ago the government allowed the farmers to convert their rice farms to fish ponds and this led to major improvements in household welfare as income from fi sh was reported to be 6-7 times higher than that from rice. An interviewed farmer said that conversion to fish ponds was illegal at first but the commune ‘turned a blind eye’ to help them improve their livelihoods through farming fish.
Following the conversion of their rice fi elds to ponds and dikes, the farmers initially used the traditional VAC system, feeding a carp polyculture with grass and rice bran but because of limited on-farm resources the yields were only about 1.5 tonnes/ha. More recently with assistance from RIA No.1, the farmers now practice improved VAC with diversification of fish species and use of pelleted feed to supplement the traditional pond inputs. Pelleted feed is mainly used to fatten fish towards the end of grow-out culture to increase profitability. Nile tilapia (Oreochromis niloticus) comprises about 70 per cent of total fish production with climbing perch (Anabas testudineus), common carp and a local catfish, Far Eastern catfish (Parasilurus asotus) comprising the other 30 per cent. There is a ready market for fish are in Hanoi and surrounding provinces.
The field trip participants had an excellent lunch on a relatively large three ha farm with steamed Nile tilapia and grilled giant freshwater prawn (Macrobrachium rosenbergii) washed down with ample bottles of local beer. The former rice farmer informed us that his total net income from this and another farm of a similar size is US$26,000/year, mainly from producing monosex tilapia fingerlings to supply local farmers and those in other provinces. Initially he nurses fingerlings in green water produced by fertilisation with pig manure, supplemented by duckweed and chopped water spinach. He also produces two crops of tilapia table fish. Nursed tilapia fingerlings of 30g size are stocked at 3/m2 with a few giant prawn post-larvae. Grow-out ponds are fed mainly pellets with a protein content of 25 per cent. Tilapia grow to 500-700g in about 6 months with an FCR of about 1.5 and a yield of 10-15 tonnes/ha. Pelleted feed costs $0.6/kg and the farm gate price of tilapia is $1.3-1.6/kg depending on size, leading to a good profit. This is a good example of a former relatively poor rice farmer considerably improving his welfare through aquaculture. Furthermore, farm profitability was considerably increased through producing fingerlings to also sell to other farmers rather than only being involved in grow-out.
We also visited a cooperative in the same area comprising 52 smaller farm households supported by RIA No.1 with Spanish Government assistance. The total area of the cooperative is 37 ha with each family having a total area of 0.6 ha of ponds, with an average pond size of 0.1 ha. A range of species are farmed: carps (common carp, grass carp and rohu), normal and red tilapia, sea bass (Lates calcarifer), striped catfish (Pangasianodon hypophthalmus), Far Eastern catfish, red-bellied pacu (Piaractus brachypomum) and giant freshwater prawn (Macrobrachium rosenbergii). Chinese carps fetch the lowest price, especially if small: 1 kg grass carp sell for only $0.3/kg although $1.4/kg if 2-3kg but $1.6-1.7 if larger than 3kg; and silver carp only $0.5/kg for a 3 kg fish. Tilapia sell for a good price at $1.3/kg for 0.5-0.7 kg fish and $1.4-1.5/kg for 0.7-0.8 kg fish. Climbing perch fetch a relatively high price of $1.4/kg for only 100g size fish. Although fish culture has considerably improved their welfare, the interviewed spokesman for the cooperative said that a big problem for the last two years was increasing incidence of fish disease, probably exacerbated by a poor water supply, and low marker price for the fish. The cooperative spokesman said they need investment for a water supply canal.
Improved VAC in Thanh Tri District, Hanoi
There is an area of 115 ha of formerly low-lying poorly productive rice fields in Dong My Commune, Thanh Tri District that the government allowed the farmers to convert into more productive improved VAC from the year 2000. Previously only one crop of rice could be successfully grown as a second crop was usually flooded. Now the landscape is one of ponds, with wide dikes created by pond excavation above the usual flood line covered with vegetables and fruit trees and livestock quarters (duck pens on or over the water and pig sties on the dikes).
I interviewed two farmers in depth, who had larger than average farms of 1.7 and 2.2 ha as they had rented and/or purchased additional land to increase the size of their original holding. Both farmers rotate more profitable prawns with a polyculture of fish; neither have livestock as they have more than enough nutrients in the water from use of pelleted feed. The first farmer stocks prawn post-larvae, PL15, 0.7 cm in size, imported from China at 25-20/m2 in May and raises them until December after which it is too cold for them to survive in the temperate climate. They are fed farm-made pelleted feed and the ponds are aerated from 10pm-6am and additionally from 3-4pm in the winter to prevent temperature stratifi cation. Prawns are harvested at intervals at 10-40 pieces/kg with a total yield of 2-3 tonnes/ha. Common carp and grass carp of 1 cm are nursed at 100/m2 in a separate pond at the same time that prawns are grown. Nursed fish fingerlings of 200-300 g are stocked at a low density of 0.7/m2 in winter in all ponds after prawn harvest and are raised from January to April to about 1 kg size. Fish are also fed some grass from pond dikes, and yield about 4 tonnes/ha. Prawns fetch US$6.4/ kg compared to $1.8-2.3/kg for carps. The farms has very poor water quality with dark green water from a bloom of blue green algae, possibly exacerbated by using home made feed with poor water stability.
The second farmer interviewed is head of the local fish farmers group, the Binh Minh Farm Club with 26 members, who organised visits to China and Thailand through a local tour group to visit prawn and fish farms. As well as prawns and carps, he also raises tilapia and red bellied pacu although some of the members do not raise prawn, only fish. Most of the club members raise tilapia as well as carps, with tilapia comprising about 70 per cent of the total production although none have only tilapia. Tilapia seed comes from local hatcheries as well as from China and Thailand. He uses commercial formulated feed as do all except two of the club members. The water supply is inadequate as it is provided only through a former rice field irrigation canal. He commented on declining water quantity and quality due to increasing urbanisation and industrialisation of the area. The future outlook he though would be stable with an adequate but not high income although tilapia began to get disease about two years ago.
A drive through the area indicated that most of the farms are growing vegetables and fruit trees on the dikes. No rice fields remained on any of the farms. Water spinach is cultivated in drainage ditches as well as some low lying pond areas to feed fish and ducks as well as humans. Some farmers cultivate duckweed on portions of the ponds separated from the main pond area by floating bamboo poles to prevent de-oxygenation of the water which occurs under a complete cover of duckweed. The duckweed is harvested periodically to feed both fish and ducks. Some farmers grow high-value ornamental plants on pond dikes for sale. A farmer reported that he could sell an ornamental fig tree for US$150. Livestock are commonly raised, especially meat ducks on small fence areas of the pond.
Traditional cage culture in Hung Yen Province
The field trip for the Small-scale Aquaculture meeting also took participants to see traditional cage culture in the Red River in Hung Yen Province where farming households do not have VAC. The farmer interviewed also has a small farm of 0.15 ha without a fish pond and raises maize, medicinal herbs and fruit but not rice on such a small land holding. He and his wife also raise a few chickens, at the time of the interview 27 birds, and previously they also raised pigs but now they said that they did not have time to do so. Their main income is from raising fish in their cage moored alongside the Red River.
Raising grass carp in wooden cages started here about 20 years ago and the number of household level cages has increased in recent years with 35 cages now in this commune alone. The farmer interviewed stocks 600 grass carp fingerlings of 300g size in a single wooden cage of 3.5 x 7.0 x 1.5 m deep dimensions, or about 20 fi sh/m3, and they reach 4-5 kg in two years. The cage lasts for three years and costs $260-320. The fish are fed grass at 20-30 per cent body weight/ day collected by the family from various sources such as their farm and locally. In the dry season when grass is limited they travel 10-15 km to collect discarded vegetable leaves removed prior to marketing. The production ranges from 1.5-1.8 tonnes/cage with fish sold at $.6-1.7/kg to middlemen who come to the cage site to purchase fi sh. Red spot disease is a problem in the rainy season.
Wastewater-fed aquaculture
Wastewater-fed aquaculture occurs in peri-urban Hanoi, in a low-lying area that receives the bulk of the city’s wastewater and urban run-off. However, the practice is declining due to urban expansion of the rapidly growing capital city of Viet Nam, Hanoi. Major roads are being constructed through the centre of the wastewater-fed pond complex with associated construction of housing and industrial complexes. Furthermore, existing villages in the area are expanding through filling in ponds.
Wastewater-fed aquaculture appears to be a transient phenomenon. Reuse of wastewater used to made sense in countries with limited sources to feed fish but once an economy starts to expand rapidly, several factors constrain wastewater-fed aquaculture: increasing shortage and value of peri-urban land; declining quality of wastewater as a nutrient source due to increasing contamination with industrial effluents and associated declining quality of produce; increasing demands of more affluent consumers for larger fish and often for species that cannot be raised profitably in fertilised ponds; and the increasing ability of farmers to meet the demand for alternative farmed species because of the availability of seed and pelleted feed through R & D and agro-industry.
