Salinity induced changes in growth and gill structure of freshwater carp, Cyprinus carpio Linn.

Abstract

Aim: The present study was carried out to evaluate salinity induced changes in the growth and gill structure of cosmopolitan freshwater carp, Cyprinus carpio (Linn.). Methodology: Inland saline water (15 ‰ or g l-1) was collected from the salt affected waterlogged areas of village Shajrana (30.3346 0N, 74.1196 0E) in District Fazilka, Punjab (India) and diluted with underground freshwater for preparing different salinity levels (2 to 10 ‰). Fingerlings (10 ±2 cm) of C. carpio were exposed to 0 (control), 2, 4, 6, 8 and 10 ‰ salinity after gradual acclimatization with salinity increase @ 1 ‰ hr-1. Results: At the end of 120 days of rearing under saline conditions, 100% fish survival was observed up to 6 ‰ salinity, while 86.66 and 70.00% survival was recorded in 8 and 10 ‰, respectively. However, fish growth declined significantly at all salinity levels (p≤0.05). Gill structure was also affected at all salinity level, but pronounced changes were observed at salinity levels ≥ 6 ‰, including lamellar oedema, epithelial lifting, lamellar hyperplasia, hypertrophy, lamellar fusion, hyalinisation, aneurysm, blood congestion, etc. Interpretation: The results offer referral database to explore optimised economic production of common carp in inland saline areas of the region at salinity levels below 6 ‰. Key words: Carp, Gills, Growth, Production, Salinity, Survival