SINGAPORE - The plankton bloom responsible for the recent mass fish deaths cannot be prevented, but steps can be taken to minimise its impact when it occurs, Minister of State for National Development Maliki Osman said.

Elaborating on these in Parliament on Wednesday, Dr Maliki said the Agri-Food and Veterinary Authority (AVA) will help farmers to develop "operationally-ready contingency plans" to reduce their future losses.

He advised fish farmers to learn from counterparts who have installed resilient systems, and to tap on the agency's Agriculture Productivity Fund to purchase the relevant equipment.

Dr Maliki also said that like last year, the AVA will not impose the minimum production requirement - 17 tonnes of fish for every 0.5 ha of farm space - on affected farms. "We understand the difficulties the farmers face during these times and will allow them sufficient time to get back onto their feet," he said.

Over the last two weeks, more than 600 tonnes of fish have died - the fourth mass death in five years - with farms near the East Johor Straits the worst-hit.

Plankton blooms can be deadly as the plankton suck oxygen from the water, suffocating other marine life. They could be caused by unfavourable environmental factors, like neap tide, dry weather, and pollution.

Dr Maliki added that his ministry is looking at what can be done to reduce pollution.

The AVA is also working with agencies and research experts to study the relationship between plankton blooms and fish kill.

It has also commissioned projects to develop closed containment systems, which would reduce the volunerability of fish stock to water conditions.

Currently, many farmers rear fish in net cages in the open sea, exposing their stock to unnecessary risks, he said. Citing Singapore Aquaculture Technologies, a company which used such a system and saved two-thirds of their stock, Dr Maliki said: "Fish farmers must consider modernising their farming methods so that they are better protected in the long term."