With fish repeatedly killed en masse in the iconic Nhieu Loc-Thi Nghe canal, which runs through several districts in Ho Chi Minh City, local experts gathered Friday for a conference to find solutions to protect the aquatic creatures.
The scientific conference was held by the municipal science department, after a total of nearly 100 metric tons of fish of all kinds have died in the canal in the last three years.
Tran Van Son, deputy head of the city’s agency in charge of protecting marine resources, said fish in the 8.7-km canal, snaking through six districts, would die during the changing season between April and May every year.
In 2014 more than ten metric tons of dead fish were recorded at Nhieu Loc-Thi Nghe, and the respective figures for the next two years were more than 20 and 70 metric tons, Son said.
Son said fish swarms have developed well in canal, which has been revitalized from a dead canal in 2012, and the fish population just got bigger as locals usually release fish into the canal as a religious practice.
However, as many locals still defy the ban to dump trash directly into the canal, the water is polluted, leading to the mass fish deaths.
Two employees pick up dead fish from the Nhieu Loc-Thi Nghe canal in Ho Chi Minh City on May 17, 2016.
In the meantime, Assoc. Prof. Vu Cam Luong, from the Ho Chi Minh City Nong Lam (Agriculture and Forestry) University, pointed to another possible cause: the canal has been overpopulated with tilapia.
While there are ten types of fish inhabiting in the canal, tilapia accounts for as many as 84.2 percent of the population, according to the professor.
“The density is seven tilapia individuals per square meter,” he said.
“While tilapia is capable of living well in the canal, it is very sensitive to environment change, evident by the fact that most of the dead fish over the last years were tilapia.”
Luong suggested reducing the population of tilapia in Nhieu Loc-Thi Nghe. “We need more intensive research to determine how much the tilapia population must be reduced,” he added.
However, Dr. Nguyen Van Hao, former head of the Research Institute for Aquaculture No.2, said Luong’s suggestion will also temporarily resolve the issue, as the root of the problem is the trash and dirty water that has polluted the canal.
The Nhieu Loc-Thi Nghe canal would be contaminated with wastewater flooded there by rainwater, plus dirty water discharged by nearby residents. It is also not uncommon to see people urinate directly to the canal.
“We should strictly control those sources of wastewater,” he said.
The Nhieu Loc–Thi Nghe canal snakes through District 1, District 3, Phu Nhuan District, Binh Thanh District and Tan Binh District. Once heavily polluted and dubbed a ‘dead canal’ back in the 1950s, it was revitalized following an expensive clean-up project, the first phase of which ended in 2012.
Other major canals in Ho Chi Minh City include Tau Hu–Ben Nghe and Tan Hoa–Lo Gom.