Most (90%) Pangasius are farmed in ponds, with some also cultured in cages and fenced areas (FAO 2009; Corsin 2009, personal communication). Cages and fenced areas are found in freshwater rivers where negative effects of Pangasius aquaculture include the spread of pollution. The negative effects of pond culture are comparatively lower because ponds are detached somewhat from waterways.

The vast majority of Pangasius farming takes place in Viet Nam, and to a lesser degree in Thailand, Cambodia, and Bangladesh. Swai catfish now accounts for more than 95% of Viet Nam’s total farmed catfish (Anonymous 2006). In Thailand and Viet Nam, approximately 7 percent of rural households are engaged in aquaculture, often in Pangasius culture (Phillips 2002). In Viet Nam, 315,000 tonnes of catfish was cultured in 2004, representing approximately 60% of the total freshwater aquaculture production (FAO 2007). Production reached 1.1 million tonnes in 2008 (Corsin 2009, personal communication).

In order to meet demands and because Swai and Basa can tolerate poor water quality, there has been a recent shift in some farms from low to high stocking density (FAO 2007; Trong et al. 2002). Both species can be successfully cultured at densities of up to 60 fish m-3 (Anonymous 2006), however, stocking densities of 20–25 fish m-3 are more commonly used (Trong et al. 2002). There is a high density of farms along parts of the Mekong River, so points were subtracted.

While governments have provided technical assistance to farmers, little has been done to implement innovative culture methods (Sverdrup-Jensen 2002). Water quality testing equipment should be more widely distributed and incentive or certification programs should be implemented to reduce water pollution (Anonymous 2006).

Some small-scale operations culture Pangasius in polyculture with Nile Tilapia and Kissing Gourami (Trong et al. 2002, Anonymous 2006). Because this is not common practice, no points were added.

Governments in Southeast Asia have emphasized fish farming development as part of their policies to alleviate poverty and diversify use of rice fields (Sverdrup-Jensen 2002). These governments are promoting low-impact pond culture and effluent treatment ponds plus developing Good Aquaculture Practices to help reduce environmental impact (Corsin 2009, personal communication).

Most farming operations for Pangasius use manufactured pellets, though some farms use home-made feed during the early stages of production or in combination with pellets (Corsin 2009, personal communication). Home-made feed is prepared by cooking rice, trash fish and/or vegetables (FAO 2007). Estimates of fish meal used in manufactured pellets range from 8 to 27 percent (Edwards et al. 2004). Often composed of bycatch and juveniles, trash fish used in the farm-made feed comes from nearby riverine and marine fisheries in Southeast Asia (Anonymous 2006). The farm-made feed is composed of between 20-30% trash fish, which are considered fully exploited (Anonymous 2006). Over 30 different species, including squid, crabs, anchovies, eel, and mackerel, are used as trash fish (Edwards et al. 2004). The Fish In: Fish Out ratio for Pangasius is generally around 0.7 (Corsin 2009, personal communication). Because most farming operations use manufactured pellets containing moderate levels of fishmeal, a score of 2 was awarded.

Pangasius fed manufactured pellets have an average FCR of 1.64 (FAO 2007). However, the FCR on farm-made feeds is considerably higher (>2) (Edwards et al. 2004, Anonymous 2006). Because most farms use manufactured pellets no points were subtracted.

Pangasius can grow on manufactured feed with low (<10%) fish meal content (Sverdrup-Jensen 2002, Edwards et al. 2004). The private sector is reducing the amount of fish products in feed (Corsin 2009, personal communication), thus points were added.

The majority of Pangasius farms in Southeast Asia are operated by small-scale farmers (FAO 2007). These low-tech operations occur in ponds and rivers where discharge is untreated. However, recent planning initiatives and regulations for the Mekong River Delta region indicate a push for more environmental protection and better safety standards (FAO 2008a,b).

While cage and fence operations release effluent and waste into the surrounding waters, water quality is already very poor (Sverdrup-Jensen 2002; Phillips 2002). Because these operations do not have a major negative impact on the local water quality, no points were subtracted.

Organic and chemical fertilizers are used in ponds, but are generally contained within the ponds and surrounding fields (Phillips 2002). There is recent evidence, however, that antibiotic resistance is increasing posing a threat to human health (Corsin 2009, personal communication), and thus points were subtracted.

Small-scale ponds are viewed as a way to recycle nutrients and organic matter for local agriculture (Sverdrup-Jensen 2002). However, there are still concerns about effluent and wastes from fish raised in cages and fences (Phillips 2002). Therefore, no points were added.

Pangasius raised in the Mekong River Delta are native to Southeast Asia (Phillips 2002, Sverdrup-Jensen 2002). Escape of Pangasius occasionally occurs during floods, but the impact is minimal because hatchery-raised catfish are genetically similar to wild catfish (Anonymous 2006). However, as hatcheries begin selecting traits favorable for farming, escapes could become a bigger concern (Anonymous 2006).

While the frequency of large-scale disease outbreaks has been rare, small outbreaks in pond farms have occurred (Sverdrup-Jensen 2002). Coupled with the occasional escape of farmed Pangasius, transfer of disease to wild population is possible.

Because Swai and Basa are native to Southeast Asia, it is unlikely that escaped fish will compete for resources or compromise the genetic integrity of wild species (FAO 2007). However, as hatcheries begin selecting traits favorable for farming, escapes could negatively affect the genetic integrity of wild populations (Anonymous 2006).

Most Pangasius are farmed in ponds that are converted from land previously used for agriculture (FAO 2007; Corsin 2009, personal communication). However, a small percentage of farms are situated on land that was cleared. Most of the Pangasius imported to the U.S. comes from the Mekong River Delta region. Water quality in this region is generally poor because of silting and insufficient waste treatment (Sverdrup-Jensen 2002; Phillips 2002). In addition, the impact of dams along the Mekong River and its tributaries on water flow and fish migration can create problems for rural households down-river (Sverdrup-Jensen 2002).

Predator deterrents are not used when farming Pangasiuis (Corsin 2009, personal communication)

Until recently, young Pangasiuis were collected from wild populations in the Lower Mekong (Chheng et al. 2005; Anonymous 2006). This practice is changing, however, and there is a growing trend toward artificial propagation of Pangasius to produce fry and fingerlings (Trong et al. 2002). Today most Pangasiuis farmers use hatchery seed (Corsin 2009, personal communication).

Governments in Southeast Asia are promoting development fish farming ponds in rice fields as a way to diversify land use and alleviate pressure on the Mekong River (Sverdrup-Jensen 2002).