Growth Responses of Fish During Chronic Exposure
of Metal Mixture under Laboratory Conditions
Saima Naz and Muhammad Javed
Department of Zoology and Fisheries, University of Agriculture,
Faisalabad, Pakistan *Corresponding author: sam_ali_3@yahoo.com
Abstract
Growth responses of five fish species viz.
Catla catla,Labeo rohita,
Cirrhina mrigala, Ctenopharyngodon idella
and Hypophthalmichthys molitrix were
determined, separately, under chronic exposure of binary mixture of metals (Zn+Ni)
at sub-lethal concentrations (1/3rd of LC50) for 12 weeks.
Randomized complete block design (RCBD) was followed to conduct this research
work. The groups (10 fish each) of Catla
catla,Labeo rohita,
Cirrhina mrigala, Ctenopharyngodon idella
and Hypophthalmichthys molitrix having
almost similar weights were investigated for their growth responses and metals
bioaccumulation patterns in their body organs during chronic exposure of Zn+Ni
mixture. The bioaccumulation of metals in the fish body organs viz. gills,
liver, kidney, fins, bones, muscle and skin were also determined before and
after growth trails under the stress of metals mixture. The exposure of fish to
sub-lethal concentrations of mixture caused significant impacts on the average
wet weight increments of five fish species.
Ctenopharyngodon idella and
Labeo rohita attained significantly
higher weights, followed by that of
Hypophthalmichthys molitrix,
Cirrhina mrigala and Catla catla.
However, the growth of metals mixture exposed fish species was significantly
lesser than that of control fish (un-stressed).
Significantly variable condition factor
values reflected the degree of fish well-beings that correlated directly with
fish growth and metal exposure concentration. Any significant change in feed
intake, due to stress, is reflected in terms of fish growth showing the impacts
of metal mixture on fish growth were either additive or antagonist /
synergistic. Accumulation of all the metals in fish body followed the general
order: liver>kidney>gills> skin >muscle> fins >bones.