At the canal entrance to Wat Paknam Bhasicharoen in Thonburi — one of Bangkok's oldest and most significant temples, straddling the Thonburi bank of the Chao Phraya — fish vendors have operated for as long as anyone can document. The fish they sell are small: walking catfish in plastic bags, bundles of freshwater eels, common carp of ten to twenty centimetres. The price is modest. The customer buys a bag or a bundle, descends to the canal edge or the temple pond, recites a Pali phrase, and releases the fish into the water.
The fish might be the same fish, purchased from the same vendor, that were caught from the same canal two days earlier. The ecology of the merit-making circuit around Bangkok's temple waterways is not always simple.
The Origin of the Practice
The release of animals as an act of Buddhist merit-making — fang sheng in Chinese Buddhist terminology, ploy pla in Thai — is ancient and not exclusively Theravada. In China, the practice is traced to the Pusa Yingluo Benye Jing, a sutra probably composed in the fourth century CE. In Thailand, the Theravada basis draws on the first precept's positive formulation: if taking life generates negative kamma, then saving life generates positive kamma. The fish vendor outside the temple gate is, in a sense, offering a service to merit-seekers by providing a life to be saved.
The canonical support for this interpretation is real but not unambiguous. The Buddha praised the intention to spare life; he did not specifically endorse purchasing market fish and releasing them as a systematic practice. The practice developed in the popular Buddhist tradition — the lived religion of lay communities — rather than being prescribed in Pali canon. This distinction matters because it means the practice has evolved in response to social and commercial factors as well as purely spiritual ones.
The Economics of Release
The fish vendors who operate near Thai temple ponds represent a specific commercial ecosystem. Their suppliers are typically small-scale fish farmers who produce walking catfish, snakehead, and common carp for this market specifically — not for food. The fish are not premium-quality food fish; they are production-line animals raised in high-density conditions on pelleted feed, sold at the smallest viable size to maximise turnover volume per rearing cycle.
This matters for several reasons. The fish are often physiologically stressed by the time they reach the vendor — transported in low-oxygen water, handled repeatedly, exposed to pathogens in the holding bags. Release into a temple pond does not always mean survival; it sometimes means delayed death in a new location. The merit generated by releasing a fish that dies within twenty-four hours of release is a theological question that Thai popular Buddhism addresses inconsistently — the intention was good, but the outcome was not life-saving.
More significant from an ecological perspective is what happens when the released fish do survive.
The fish vendors outside Bangkok temple gates represent a specific commercial ecosystem, supplying animals raised not for food but specifically for release — a market that creates its own incentives entirely disconnected from any conservation logic.
The Invasive Species Problem
The Thai Department of Fisheries has documented, with increasing specificity over the past decade, the ecological consequences of unrestricted merit-release in natural waterways. The problem is most acute with non-native species: Nile tilapia (Oreochromis niloticus), suckermouth armoured catfish (Hypostomus plecostomus and related species, commonly called pla hang daeng or pla kong locally), and red-eared slider turtles (Trachemys scripta elegans).
All three are routinely sold outside Thai temples. All three are invasive species that have caused documented ecological harm in Thai waterways. The armoured catfish — a South American aquarium species introduced to Thailand decades ago — has established breeding populations in canals and rivers throughout the country, where it competes with native species for habitat, disturbs spawning beds, and has no natural predators of comparable effectiveness. Its spread is substantially attributable to merit releases.
Red-eared sliders, native to North America, have become the dominant turtle species visible in many Bangkok canal systems and provincial temple ponds, displacing the native soft-shell turtles (Amyda cartilaginea and Chitra indica) that once inhabited these waters. The trade operates openly — slider turtles in small bags are sold at temple gates as merit-release animals — despite the species being recognised as one of the 100 Worst Invasive Species by the IUCN.
Temple Ponds as Closed Systems
Not all merit release goes into open waterways. Many temple ponds are partially or fully closed systems — concrete-lined or lined with impermeable soil, without significant connection to rivers or canals. In these ponds, the ecological concern shifts from invasive species spread to biomass accumulation and water quality.
A temple pond that receives merit-released fish daily without any removal mechanism accumulates fish biomass over time. The ponds at major Bangkok temples with significant visitor traffic — Wat Pho, Wat Arun, Wat Saket — contain dense populations of large fish, many of which have lived in the pond for years and grown to sizes that merit-bought fingerlings would take decades to reach. These fish are never harvested; they are Buddhist sanctuary residents.
The water quality consequences of high fish density in these closed ponds are managed with varying effectiveness by temple staff. Some ponds have aeration systems. Some receive partial water exchanges from connected canals. Many do not. The dense, low-oxygen, high-nutrient water that results creates conditions that are stressful for fish — particularly for species like common carp that require relatively clean, oxygenated water — and that support the growth of harmful algae and anaerobic bacteria.
The large fish in these ponds are not, in most cases, thriving in the ecological sense. They are surviving in conditions that a sport-fishing venue would be required by its own commercial incentives to improve. The merit that accumulates from releasing them is real; the welfare conditions of their residence are frequently not.
Progressive Temple Responses
The ecological critique of merit-release fishing has not gone unheard in Buddhist institutional circles. Several urban temples with environmentally aware abbots or educated lay committees have taken steps to address the worst aspects of the practice.
Wat Chak Daeng in Samut Prakan, known for its recycling and environmental initiatives within the Buddhist framework, has signage at its water entry points specifying appropriate release species — native fish only, no suckermouth catfish, no turtles — and has worked with local fisheries officers to create a managed stocking program for its pond using native species. The temple frames this not as environmental regulation but as dharma practice: the most beneficial merit-making is that which causes the least harm.
Several temples in Chiang Mai and Chiang Rai have similarly engaged with the invasive species problem, partly motivated by the mahseer conservation context that is more culturally present in northern Thailand than in Bangkok. A temple pond release of suckermouth catfish in Chiang Rai, where the fish would eventually reach wild mahseer rivers, carries cultural weight beyond the generic ecological argument.
The Sub-Culture of the Regular Releaser
Alongside the occasional merit-maker who releases fish once or twice a year at major religious occasions — Songkran, Makha Bucha, Visakha Bucha — a distinct sub-culture of regular fish-releasers has emerged in Thai Buddhist practice. These are individuals who release fish weekly or even daily, treat the practice as a primary devotional act, and have developed detailed personal protocols around species selection, timing, and location.
This sub-culture is predominantly female, predominantly middle-aged, and predominantly urban. It intersects with the fishing community at the point of merit-release venues near pay-lakes and fishing parks, where regular releasers purchase fish from vendors who have learned to stock the species these customers prefer. The social world of the regular releaser is distinct from the social world of the regular angler, though they sometimes share physical space at venues where both activities are available.
The merit-release sub-culture has its own social media presence — Facebook groups, LINE communities, Instagram accounts — where members share information about release locations, discuss species choices, post photographs of large fish being released, and accumulate the social recognition that reinforces devotional practice. It is a devotional community that has adopted social media communication strategies in ways that more traditional religious practices have not.
Understanding this community matters to anyone interested in Thai fishing culture because it represents one of the clearest expressions of the Buddhist-fishing interface in contemporary Thai life: fish as objects of both sport and spiritual practice, the same waters serving both the angler and the merit-maker, the same species the target of both a hook and a prayer.