RESUMO
Abstract The effects of oral oxytetracycline (OTC)-therapy against Aeromonas caviae infection as well as the wound progression and healing in intramuscular (IM) and abrasion-immersion (AI) challenged Nile tilapia juveniles were evaluated. The IM challenge caused significantly (p < 0.05) high mortalities (90%) compared to AI challenge (40%). The mortalities recorded in 10 days OTC-fed (72% in IM group and 30% in AI group) and untreated Nile tilapia were significantly (p < 0.05) high compared to positive (5-10%) controls. The reduction in mortalities in OTC-fed Nile tilapia was significant (p < 0.05) with no further mortalities during the post-OTC therapy period. In IM group, the black scar disappearance, re-growth of dermal fibrous tissue and skin growth at the ulcerated region were seen on day 10 OTC-therapy. In contrast, the disappearance of wound scar and growth of skin and scales at the abraded area were noted on day 1-4 post-OTC therapy. On day10 post-OTC therapy, complete disappearance of wound scar with a mild spot at the abraded area was noted. The degree of wound healing was faster only initially with OTC- therapy. Nevertheless, the wounds were healed completely even in the surviving untreated tilapia in 30 days with no scars left behind. The extent of mortalities observed in Nile tilapia during the OTC-therapy period is a serious cause for concern, which require prudent planning on its suitability in tropical aquaculture.
