RECORD ON CAUDAL FIN DEFORMITY IN SILVER POMFRET Pampus argenteus (EUPHRASEN, 1788) FROM INDIAN WATERS
Deformity is one of the major concerns which affect many organisms since 16th century biologists have focused towards the deformities in fishes. There are different sorts of deformities like skeletal deformity, vertebral deformity, fin deformity (Pelvic, Caudal, Anal, Absence of fins), jaw deformity, scale deformity and colour abnormalities (ambicolouration, albinism, and xanthochroism). There are so many factors like xenobiotic, environmental, nutritional, physiological and genetic factor playing vital role for the deformity in both wild and cultured fishes. The present paper is the documentation of incomplete form of caudal fin in a wild-caught silver pomfret Pampus argenteus (Euphrasen 1788) from Indian waters. Upon further examination of the specimen and literature survey, it is inferred that such deformity in silver pomfret has been documented in limited numbers from Indian waters.
This deformed individual was collected during the routine observation of trawl catch, from Jegathapattinam fishing harbour Palk Bay, Tamil Nadu (N 9.962134, E 79.185584) on 2nd March 2018. Among the specimens of silver pomfret collected a specimen with incomplete form of caudal fin, was recorded and brought to the laboratory for further examination. The fish was caught from Palk Bay at a distance of 20 km from the seashore at the depth of 25 m in the southeast direction of Jegathapattinam by a trawler. The X-ray of the deformed specimen was taken for analysis.
Generally, a deformity of structure in fishes includes kyphosis, lordosis, scoliosis, platyspondyly and vertebrae fusion. The incomplete forms of dorsal and ventral procurrent ray were found. Further the caudal fin was found incomplete. It is understood that during the early developmental stage, development of caudal fin skeleton might have been affected by some environmental factors or due to predation and in due course, the wound might have healed and the individual could survive even with the extreme malformed condition (Jawad et al. 2013).
Divanach et al. 1996 reported that there have been numerous reports by several authors on various types of deformities in wild and cultured fishes, physical deformity lead to major economic loses in hatchery. To avoid economic losses in hatchery production factors such light, heat exposure, effect of photo and thermo-period induction during reproduction, swim bladder activity and water quality must be monitor keenly. However in the wild condition, such a phenomenon is rarely observed. Even though exact reason for the cause of deformity is unknown, the reoccurrence if happens in future may help to arrive at some scientific clue
