'Marble-stuffed hilsa scam' deceives buyers in Bangladesh
A Bangladeshi student claims to have uncovered a scam in the city of Barisal to increase the weight of hilsa fish so that they become more expensive.
Police say the fishmonger accused of the fraud has gone into hiding.
Hilsa is a much sought-after Bengali delicacy: the Indian PM on a recent visit to Dhaka said that he was tempted to give up vegetarianism to eat it.
Bangladeshi traders export large quantities of Hilsa fish to neighbouring India and Western Europe.
Masraful Islam Shaikat alleges that the glass balls were deliberately put inside the fish to make them heavier.
"I bought six hilsa fish from a fishmonger in the Barisal market and asked another man to cut them.
"To our surprise, we found 20 marbles in one fish and another 15 in the second one," Mr Shaikat, who is a student of Barisal Medical College, told the BBC.
"Initially, we thought the fish might have swallowed the marbles accidentally, but the high number of marbles triggered our suspicions.
"I think the fishmonger was greedy and he deliberately stuffed them inside the fish to increase its weight."
Hilsa is normally sold for around $9 (£6) a kg and traders say if the weight of an individual fish crosses a kg, then the price doubles.
Mr Shaikat has lodged a complaint with the Barisal traders' association.
The association says it is taking action against the fishmonger.
"This is totally unacceptable and this incident has tarnished our image. We have filed a complaint with the police against the seller for indulging in an unlawful method to boost his profits," Nizam Hossain Tutul of the Barisal Fish Traders' Association told the BBC.
Mr Shaikat says he ate the hilsa with his family - minus the marbles - and they tasted "normal".