Hematological changes in Tinca tinca after exposure to lethal and sublethal doses of Mercury, Cadmium and Lead

Tench, Tinca tinca, were exposed to three treatments (one acute lethal 96 hrs Lc50/48 hrs and two chronic sublethal 10 and 25% Lc50/504 hrs) each of Mercury, Cadmium and Lead and its behaviour as an indicator of impaired hematology was studied. It was observed that impairments in hematological parameters (increased/decreased Hct, Hb, RBC, WBC and Lct) were reflected in behaviour of fish in the form of hyperactivity, increased breathing, accelerated ventilation with rapid arrhythmic opercular and mouth movement, frequent surfacing and sinking, erratic swimming, gradual onset of inactivity, lethargy, loss of equilibrium, revolving and convulsion on exposure to heavy metal treatments. It was concluded that possibly four physiological systems (i) faulty gaseous exchange at gills, (ii) stress mediated hormonal imbalance, (iii) impaired osmoregulation and (iv) disturbed metabolism were involved in hematological impairments and their reflection in the behaviour of fish.