Hilsa is Bangladesh’s national fish. Locally known as ilish, it is cherished as the queen among fish and forms part of the culinary identity of both Bangladesh and the bordering Indian state of West Bengal.

Former Bangladeshi Prime Minister Sheikh Hasina used the fish – which is found in the Bay of Bengal and in rivers – as a tool of diplomacy to foster ties with its western neighbour, India.

But Bangladesh’s interim government’s decision to briefly ban exports of the fish to India in September caused a culinary crisis of sorts ahead of the festival of Durga Puja in India. Hilsa fish cooked in mustard sauce is a popular delicacy during the festival. Some experts viewed the move as a diplomatic rebuke for New Delhi’s backing of Hasina, who has taken shelter in India after her removal in late August.

Dhaka insisted the ban aimed to reduce the cost of the freshwater fish domestically amid a leaner harvest this year. It, however, reversed its order within two weeks.

So what is the fish at the centre of it all, and is it more than just a popular meal?

What is hilsa, the fish at the centre of the India-Bangladesh diplomatic row?

Bangladesh exports 70 percent of the world’s hilsa. But the prized catch is increasingly becoming rare and expensive, owing to overfishing, increased demand and environmental challenges like climate change.

Fishermen this year say they are also struggling to catch adequate amounts of hilsa due to rough sea conditions.

The exports add to the scarcity, with the fish unaffordable to most Bangladeshis due to its high cost. In 2024, the price of a 1.5kg hilsa fish reached about $15 (1,800 Bangladeshi taka) in local markets, compared with about $10.9 (1,300 taka) last year.

At 550,000 to 600,000 tonnes a year, hilsa contributes about 12 percent of Bangladesh’s total fish production, supporting approximately 500,000 fishers directly and two million people in related industries.

Some cherished staples of local cuisine include bhapa ilish (steamed hilsa), ilish polao (pilaf rice with hilsa), and shorshe ilish (hilsa in mustard sauce).

Did Bangladesh impose a ban on hilsa exports to India?

In September, Dhaka imposed an export ban on hilsa, specifically targeting shipments to India. This came in the run-up to the Durga Puja festival in October when demand typically peaks across the border.

Fisheries officials explained that the ban was necessary to prioritise domestic supply and manage the declining hilsa population.

“We cannot allow ilish to be exported while our own people cannot buy them. This year, I have instructed the Ministry of Commerce to prevent any ilish exports to India during Durga Puja,” Farida Akhter, adviser to the Bangladesh Ministry of Fisheries and Livestock told the Dhaka Tribune.

However, weeks later, the Commerce Ministry reversed the ban and approved a 3,000-tonne shipment to India.

“Against the backdrop of appeals by the exporters, approval has been given to export 3,000 tonnes of hilsa fish (to India), fulfilling the specific conditions on the occasion of the upcoming Durga Puja,” read the ministry’s statement.

Hilsa prices have shot up sharply in India as Dhaka reduced exports by 1,000 tonnes. But the government has failed to bring down the prices in Bangladesh.

“A syndicate of fishermen who smuggled hilsa to India kept the price high,” said Khandakar Tahmid Rejwan, a research data analyst at the Bangladesh Peace Observatory under the Centre for Alternatives.

An expert from India said the brief ban marked “a firm departure” from Hasina’s practice of using the fish as a symbol of goodwill and friendship between Dhaka and New Delhi.

Hasina first used the fish as a diplomatic tool when she came to power in 1996. She gifted hilsa to then-West Bengal Chief Minister Jyoti Basu ahead of a landmark agreement on sharing water, a major bilateral issue between the neighbours.

In 2016, the former Bangladeshi prime minister sent a consignment of hilsa to Mamata Banerjee, who heads the government of West Bengal bordering Bangladesh. A year later, former President Pranab Mukherjee, a prominent Bengali leader of the time, was gifted hilsa as a gesture of friendship.

But the interim government is likely to diverge from Hasina’s pro-India foreign policy, according to an expert on India-Bangladesh relations.

The move by the interim government “compromises the goodwill” between the two nations, Sohini Bose, associate fellow at the Observer Research Foundation in Kolkata, told Al Jazeera via email.

Is this the first such ban?

No.

Bangladesh imposed a ban on hilsa exports to India in 2012 following disputes over a water-sharing agreement. This was eventually lifted in January 2018 as a goodwill gesture.

Additionally, over the years Hasina’s government frequently made exceptions to the ban by “gifting” hundreds of tonnes of the fish ahead of Durga Puja.

Bangladesh also periodically imposes local bans on fishing hilsa to protect it during breeding periods.

The main ban is enforced for 22 days during October and has been a practice since 2007. This restriction during hilsa’s spawning season gives it time to reproduce undisturbed.

The downside is that this poses economic challenges for fishermen, many of whom rely on hilsa for their livelihood.

Hasina has also gifted locally made sarees and mangoes to leaders across the border.

In 2021, Hasina reportedly sent 2,600kg of Haribhanga mangoes to Indian Prime Minister Narendra Modi and West Bengal Chief Minister Mamata Banerjee.

The gesture came as Bangladesh faced a delay in the supply of COVID-19 vaccine doses from India.

Why are ties between India and Bangladesh strained?

India backed Hasina until the end of her 15-year rule, which rights group say was marked by human rights abuses, electoral manipulations and a crackdown on opposition parties.

New Delhi also observed silence on a government crackdown that killed more than 300 protesters, shortly before she fled Bangladesh. India’s hosting of Hasina has not gone down well with the interim government, which has sought Hasina’s extradition – a demand New Delhi is unlikely to honour.

Many in Bangladesh perceive New Delhi’s backing of Hasina as enabling her heavy-handed approach.

In her 15-year rule, Hasina fostered close ties with India, particularly through security cooperation agreements, which critics and opposition parties said were biased in favour of New Delhi.

Vilification of Bangladeshis by the Hindu nationalist government in India as “infiltrators” and “termites” has also angered Bangladeshis. Last week, Dhaka condemned “a highly deplorable” speech by Indian Home Minister Amit Shah.

Addressing a political rally in the eastern state of Jharkhand, Shah said if a BJP government was elected in the state, “We will hang every Bangladeshi infiltrator upside down to give them a lesson”.

Dhaka has also complained about the killing of its citizens at the border by India’s Border Security Force. Rights groups have slammed the “unlawful killings and abuse of Bangladeshi people at the border”.

Rising Islamophobia and attacks against Muslims under Modi have also instilled anti-India sentiments in Bangladesh.

Moreover, the Hasina government’s trade deals with Indian corporations also came under scrutiny, with critics accusing her of signing deals that benefitted Indian companies.

The Teesta River dispute also remains a major point of contention between Bangladesh and India, as both countries rely heavily on its water for agriculture. Bangladesh has long sought a fairer allocation of the river’s flow, arguing that the current arrangement – controlled primarily by India – causes water shortages during the dry season.

Additionally, the sudden release of water during heavy rainfall has contributed to flash floods in Bangladesh, including in August this year.

Officials at Bangladesh’s Flood Forecasting and Warning Centre told Al Jazeera that unlike in the past, India did not issue a warning to its neighbour about the release of water last month. India’s Ministry of External Affairs dismissed the reports, calling them “factually not correct”.

India, particularly its West Bengal state, has resisted changes to the existing river-sharing agreement, citing its own agricultural needs.

India’s ties to Hasina’s party, the Awami League, go back to when the party was fighting for liberation from Pakistan in the 1970s. New Delhi has cultivated close ties with the secular Awami League and has seen the opposition Bangladesh Nationalist Party and Jamaat-e-Islami as soft on Pakistan.

What have the two countries said about the diplomatic tensions?

Interim leader Nobel laureate Muhammad Yunus has called for a reset in relations. Earlier this month, he criticised Hasina for giving directives from her haven in India, adding that her continued interference in Bangladeshi politics could exacerbate tensions.

He has also warned India to move away from its narrative that Islamist forces, supported by groups like Jamaat-e-Islami, are overtaking the country.

India’s Fish Importers Association earlier this month in a letter urged Dhaka to allow exports of the fish, especially for the festival.

What’s the future for India-Bangladesh ties?

Rejwan, the researcher based in Dhaka, says “the resentment that was building in common people is reflecting in a more formal diplomatic channel”, adding that previously the relationship was only warm at the highest level.

He says, however, that there is potential for India and Bangladesh’s relationship to be mutually beneficial, but that it must be based on equity and see progress with key issues such as border killings.

“If the government fails to address these and maintain a balance with New Delhi, then it will be perceived as similar to Sheikh Hasina’s regime,” he added.

Bose from the Observer Research Foundation believes the two countries have the potential to improve relations due to the existing, “natural” interdependence.

“With adjacent territories across the world’s fifth-longest boundary, Bangladesh and India have several common resources from trade of daily essentials to familial connections,” Bose said.

“This geographic reality is indisputable despite any political transition, which makes it necessary for India and Bangladesh to maintain a functional relationship.”