Is the occurrence of dragonets fish (Callionymus carebares and Callionymus profundus) in the coastal waters of Bangladesh natural or incidental?

Abstract

New fish species are being reported outside the frontiers of their natural territory. The Bay of Bengal with its adjacent coastal waters is an ideal habitat for diversified fish species. Recently, two dragonet species belonging to the Callionymidae family were discovered from the inshore coastal waters in the southern region of the Bay of Bengal, constituting a new record in the territorial waters of Bangladesh. After observing a specimen of callionymid species in a landing center, six sampling points were selected to confirm the presence of the species and the survey continued for six months. With the hauling of set bag nets and gill nets by fishermen, a total of 13 specimens of dragonets were captured from five sampling sites over the sampling period. The species, identified as Callionymus carebares and Callionymus profundus based on their morphological features, are not native to the region. We confirmed 9 specimens of C. carebares and 4 specimens of C. profundus in the laboratory with body weight ranging between 7.29–19.63 g and 5.2–9.83 g, respectively. Though the definite reasons of their occurrence in this new territory are yet to discover, the species C. carebares possibly migrated from the nearest native habitat in southwestern coastal regions of India; on the other hand, C. profundus, has only been previously reported from the northern regions of the Red Sea in Israel.