EFFECT OF OZONATED WATER TREATMENT ON CLINICAL SIGNS, SURVIVAL RATE AND HISTOPATHOLOGICAL ALTERATIONS IN COMMON CARP, CYPRINUS CARPIO L. INFECTED WITH SAPROLEGNIA SPP.

Abstract

Present study was undertaken to assess the efficacy of Ozone and formaldehyde (as a reference treatment) on controlling Saprolegniasis in common carp, Cyprinus carpio L. Saprolegnia spp. were isolated on special culture media for fungi from 50 infected specimens of fishes were identified as Saprolegnia spp. Viable fungal suspension of Saprolegnia was determined and adjusted at a concentration of 2×104 zoospores l-1 . To control this fungus, a total of 120 common carp weighing 80±10g were randomly distributed into six replicated groups (10 fish/replicate) and were treated as follows; C-: control healthy without treatment; C+: control infected with Saprolegnia spp. without treatment; T1, T2 and T3: fish were infected with Saprolegnia spp. and treated with Ozone 0.25, 0.50 and 0.75 mg/l per hour respectively; T4: fish were infected with Saprolegnia spp. and treated with formalin 0.15 ml/ l for 30 min for 3 successive days. Clinical signs and survival rate were studied. After 14 days of treatment with Ozone, samples were collected from fish for histopathological studies. Among the Ozone treatment 0.50 mg/l showed highest survival rate (90%), survival rate of the control group (without disinfectant) was 20%. Histopathological studies revealed significantly increased (p<0.05) percentage of gill epithelial proliferation and epithelial lifting, also fusion of the secondary lamellae, in fish from ozonated groups relative to C+ and C- groups. However, there were no significant differences in histopathology frequency/severity among the ozonated groups (T1, T2, T3 and T4). Skin of C+ group exhibited severe histopathological alterations including sloughing, erosion and ulcerative of epidermis penetrating up to dermal tissue. While Ozone treatment groups showed increase number of mucous cells and MNCs infiltration. Ozone appears to be a valuable disinfectant against Saprolegnia infection; at the dose of 0.50 mg/l. In conclusion, the results indicated the efficacy of Ozone as antifungal in controlling Saprolegnia infection. Thus, Ozone could be used as potential and promising alternatives to chemotherapeutics compounds in aquaculture, to achieve sustainable, economic, and safer fish production