Use of chemoprophylactic agents in the management of <i>Clarias gariepinus</i> seed production

Abstract

Some chemotherapeutic agents and procedures haveshown toindividually enhance fish egg hatchability. This paper reviews the use of such disinfectants (iodine, formaldehyde and hydrogen peroxide), antibiotics (ciprofloxacinmetronidazole), procedure (egg washing) and their combinations on Clarias gariepinus hatchability. One thousand eight hundred each of washed and unwashed fertilised eggs obtained from both parenteral, prophylactic ciprofloxacin-metronidazole treated (each 10mg/kg) and untreated broodstock, were disinfected by bath for 15 minutes in three recommended disinfectants: hydrogen peroxide (H₂O₂; 83.3, 166.7 and 250 ppm), povidone-iodine (33.3, 66.7 and 100 ppm) and formaldehyde (333, 667 and 1,000 ppm), incubated at 26^oC and hatchability determined. Appropriate controls were set up, data analysed using standard tests at α0.05. Hatchability significantly improved with egg washing (40.1%), antibiotics (39.8%), 250 ppm H₂O₂ disinfection (23.5%), over the control. The combination of egg washing and 166.7 ppm H₂O₂ disinfection, antibiotics and 83.3 ppm H₂O₂ disinfection; antibiotics and egg washing improved hatchability by 53.4%, 50.8% and 46.7% over the control, respectively. Antibiotics, egg washing, disinfection with 83.3 ppm H₂O₂ combination gave the highest hatching rate of 76.8%. To prevent drug resistance, egg washing and166.7 ppm H2O2 disinfection combination is recommended for routine Clarias gariepinus egg management.