Gill morphometrics of freshwater Tilapia zillii as an indicator of fish welfare

Abstract

Tilapia zillii was used to examine the effect of environment on gill morphometric therefore to discover the probability of using gill morphometrics to measure welfare in wild fish.  Thirty mature Tilapia zillii was collected from Lagoon of Ain-Ziyana  in eastern of Benghazi city and the sizes of their gills were estimated.  The gill respiratory surface area of Tilapia zillii reached from 851.31 mm² to 1929.32 mm² ̸ g of body weight. The connection among gill respiratory surface area and fish body weight was found to be highly significant (P= 0.001). The gill respiratory surface area of Tilapia zillii rise as the fish grows this may be since the gill filaments number, the secondary lamellae number and the surface area of secondary lamellae increases. Great gill surface area might support survival of Tilapia fish in oxygen-stressed.  This recommends that the measure developed here could be possibly used as an guide of welfare in wild fish.