A rare species of fish, called signal fish, that has a unique colour pattern and flips up its extended dorsal fins to signal each other, was identified from the coastal region of Kerala in 2015. Last month, a study on the species was published in the Journal of the Ocean Science Foundation (JOSF).
This is the first species in the genus to be identified in Indian waters. The fish was first found in the Lakshadweep Sea off the Kerala coast during a marine survey by scientists from the University of Kerala and the Ocean Science Foundation, USA. The study was conducted over four years by A Biju Kumar, Professor and Head of the Department of Aquatic Biology and Fisheries, University of Kerala, and Ben Victor of the Ocean Science Foundation and published in JOSF.
Speaking to TNM, Biju Kumar says, “It’s a species that is found in deep sandy habitats, in waters below 50 m, usually close to coral reefs. So its existence shows the presence of coral reef off the Kerala coast, which needs to be preserved.”
Apart from the typical flipping of the fins, the newly identified signal fish, Pteropsaron indicum, also has bold yellow markings on its body to grab the attention of its fellow mates. Its body is covered by large cycloid scales. “The head and body are a pale greyish pink, criss-crossed with dark margins of large scale pockets,” the study describes.
“The species are typically tiny and fragile (most less than 50 mm SL, and some less than 30 mm SL) and usually found below normal diving depths, more than 50 m deep (several species are bathydemersal, below 200 m). The new species of Pteropsaron from Indian waters is distinctly larger and appears in local deep trawl samples,” the study further says.
Biju says that they found three fish over the period of their study, which have been deposited at the Western Ghat Field Research Centre, Zoological Survey of India, Kozhikode and the Department of Aquatic Biology and Fisheries, University of Kerala.
Biju tells TNM that four signal fish species have been identified all over the world and that they are very rarely seen.
“Recently the fish are being kept in aquariums as they are rare and need to be conserved. They cannot be spotted easily in the natural marine system,” he says, adding that it is a poorly studied group of fish.