Scientists in West Bengal have officially identified a new species of estuarine fish, a discovery that suggests many more creatures may be hiding in India’s vast river systems. Researchers from Tamralipta Mahavidyalaya and Vidyasagar University found the fish in the Rupnarayan River near Tamluk, West Bengal. The new species, named Butis bargabhimae, belongs to the butid family, a group of fish commonly known as gudgeon goby that typically live in the brackish waters where rivers meet the sea.

The discovery was made between June 2022 and August 2024 through a collaboration between scientists and the local community. Fishermen using traditional hand nets and trawl nets collected seven specimens that caught the researchers' attention. While these fish looked similar to known species, closer inspection revealed they didn't quite match any existing descriptions. To confirm their suspicions, the team conducted a detailed analysis that included both physical measurements and DNA testing.

What sets Butis bargabhimae apart from its closest relatives is a series of specific physical traits. While most of its cousins have smooth areas around their eyes, this new fish features unique scales between its eyes (known as interorbital scales) and additional auxiliary scales across its body. It also sports distinctive light and dark bands on its pectoral fins, which are missing in similar species. Perhaps most significantly, the team’s laboratory work revealed that the fish’s DNA is only about 86% similar to its nearest relatives, providing genetic proof that it is a distinct branch on the tree of life.

The naming of the fish reflects the connection to the region where it was found. The species name, bargabhimae, is a tribute to the Hindu deity Bargabhima, a significant cultural and religious figure in the Tamluk area of West Bengal. By naming the fish after a local deity, the researchers have created a permanent link between the region's natural biodiversity and its cultural heritage.

This discovery also helped scientists clear up some long-standing confusion in the world of fish biology. By comparing the DNA of their new find to international databases, the researchers realised that several fish previously caught in Bangladesh and other parts of India had been misidentified. It turns out those fish likely belonged to this new species all along, or were other relatives being mistaken for common types. The study highlights how much remains to be learned about the wildlife living in India’s backyard.