Preliminary studies of gamma radiation effects in male nile tilapia fishes (Oreochromis niloticus) (Linnaeus, 1759)

Abstract

Surveys about the response of fish species subjected to ionizing radiation are still sparse. The
present work aimed to evaluate the resistance of tilapia subjected to gamma radiation doses
absorbed in the whole body: 0Gy, 5Gy, 10Gy, 20Gy, 39Gy, 77Gy and 154Gy. For each
dosing interval, two male specimens were used. Fishes that received doses 5Gy, 10Gy and
20Gy, showed a normal behavior on food intake and in pattern of displacement in the
aquarium, showing neither neurological damages nor deaths. Those who received 39Gy,
77Gy and 154Gy, demonstrated lack of appetite and signs of spatial disorientation 11 days
after radiation, on average. In four of the six subjects the development of lesions in the soft
tissue body surface was observed. Fishes that received 39Gy developed tumors and an animal
who received 77Gy developed a cutaneous lesion near the dorsal fin. For those who received
154Gy, a fish developed an apparently necrotic cutaneous lesion near the tail. In the group
that received 39Gy, the survival period was an average of 12.5 days, for the fishes which
received 77Gy; 11.5 days and in the group of 154Gy, 10 days.