Ilish, or hilsa, rules the hearts of Bengalis. And, over the past few years, it has been breaking their hearts as well. The high demand for ilish has led to over-fishing and the catch has been decreasing steadily and alarmingly over the past decade. Many Bengalis, alarmed over scientists' warnings about the fish's imminent extinction, are disconsolate about the prospect of even contemplating life without ilish. Especially the ilish from the Hooghly in West Bengal or Padma in 'Opar Bangla' (the Bengal on the other side of the river, as Bangladesh is referred to often).

Bengalis, depending on which side of the border they're from - 'Ghotis' from West Bengal and 'Bangals' from erstwhile East Bengal - debate passionately about the taste of ilish from the Hooghly or the Padma. The 'Ghotis' expectedly wax eloquent about Hooghly's ilish and their 'Bangal' cousins sneer at such lowly claims. But they're united in their opinion that it's only the ilish caught from these two rivers that's worth putting on the table. Ilish from the Irrawady in Myanmar, or the Tapti in Gujarat, is simply not worth even talking about, forget biting into. But then, little do most Bengalis know that at least 40 per cent of the ilish available in Kolkata's markets is from the Tapti, and about 10 per cent of what's imported from Bangladesh is from the Irrawady. This piece of news would be enough to infuriate any Bengali worth his mustard oil, and that's why people like Syed Anwar Maqsood, secretary of the Bengal Fish Importers Association, prefer not to talk about it.

But one can't really blame Maqsood and his ilk. The demand for ilish far outstrips supply from the rivers of Bengal and Bangladesh and the seashores. Ilish is anadromous in nature : it matures into an adult in the sea and spawns in rivers. "During monsoons, when the swollen rivers bring a lot of fresh water to the sea and the east wind blows, shoals of hilsa with roe in their bellies start swimming upstream along the rivers to spawn. After spawning, they travel back to the sea. The eggs hatch and the young fish stay in the river water for a few months before swimming back to the sea to grow, mature into adults and procreate, " says Arup Das, a fish expert at the West Bengal University of Animal and Fishery Sciences. It is this nature of ilish that not only gives it the unique taste that sends Bengalis into raptures, but is also its nemesis. "Ilish should be caught only during its downstream journey. But the huge demand for this fish has led to fishermen catching ilish with roe in its belly and also the young fish (called 'khoka' ilish, 'khoka' meaning lad in Bangla) during its journey to the sea to mature. So if the young ones are caught even before they mature and can procreate, and the female fish with roe is caught, it's inevitable that ilish will become extinct, " says prominent musician and foodie Nondon Bagchi. Bengal's fisheries minister Abu Hena blames Bengalis' "round-the-year greed" for ilish for the crisis. "Traditionally, Bengalis would not consume ilish after 'Dashami' (the last day of the Durga Pujas, usually in end-October ) and Lakshmi Puja (in mid to late-February ) to allow the 'khoka' ilish safe passage to the sea. Fishermen used to throw back most of the ilish with roe in their bellies from their nets back into the water. Now, an ilish with roe is in greater demand and Bengalis want ilish throughout the year, " he says. The minister admits that a ban on catching or selling ilish weighing below 500 grams has had little effect because of difficulties in implementing it. Rising pollution in the Hooghly has also led to declining catches. Rakhi Purnima Dasgupta, who has authored books on Bengali cuisine and runs a popular Bengali food restaurant, says the ilish from Gujarat is bland. "Maybe it has something to do with the river, " she adds. Fish expert Das agrees: "The rivers of Bengal carry a lot of detritus and planktons that the ilish gorges on. The Tapti doesn't. So the taste may be different. " But then, many Bengalis have been eating the ilish from the Tapti and have not been able to tell the difference. The chef of a prominent chain of restaurants specialising in Bengali food says such Bengalis are "upstarts" who can't tell mustard oil from groundnut oil.

But what if ilish were to disappear from both the Hooghly and Padma? Would Bengalis here, like their expat cousins in the US, consider shad as an alternative? "No way. Ilish is ilish and there's no alternative to it, ' says Bagchi emphatically. Dasgupta would rather go without 'Banglar ilish' than be caught having ilish from Gujarat or shad. In fact, that's what fish experts recommend: that Bengalis forego their ilish for a couple of years at least to allow the fish to return from the verge of extinction. But will Bengalis make this supreme sacrifice ? Or can they? "Will humans stop driving because the world has limited reserves of fossil fuels, " asks food columnist Anjan Banerjee. Well, you have your answer there.