Effects of commonly used disinfectants on bacterial load, hatchability and survival of Bluefin Sea bream (Sparidentex hasta) eggs

The efficacy of four chemical reagents, iodophor, formalin, hydrogen peroxide and bronopol as fish egg surface disinfectants were evaluated in bluefin sea bream (Sparidentex hasta). Fertilized eggs were counted and subjected to a static bath dip treatment in different concentrations of the above chemicals for 4min before being incubated at 20 +/- 0.5 degrees C for 40h. Treatment efficacy of the different disinfectants was evaluated by assessing the bactericidal activity, egg hatch percentage and survival of larvae up to 3days post hatch. Results showed that iodophor at medium concentrations (75 and 100ppm) was the best of all tested disinfectants in bacterial killing ability (12% reduction in the bacterial counts), egg hatching per cent (99.8% and 99.6% respectively) and larval survival up to 3days post hatch (50.8% and 54.8% respectively). Formalin was the second best disinfectant at levels of 100 and 150ppm. Hydrogen peroxide gave good results compared with the control while, bronopol showed discouraging results. In conclusion, iodophor appeared to be suitable for bluefin sea bream eggs disinfection with a 4min exposure to 75-100ppm when applied 14-16h after egg fertilization.