Abstract
Because of its bactericidal properties, tannic acid was evaluated as a potential egg disinfectant for rainbow trout Oncorhynchus mykiss. After water hardening, eggs were disinfected with tannic acid (2, 20, or 200 mg/L for 5 or 15 min) or with iodine (100 mg/L for 10 min; control). Hatch (83.7–93.4%) and deformity percentages (<0.8%) did not significantly differ among treatments. Bacteriological data indicated that the percentage of eggs with no bacteria was significantly higher from the iodine treatment (87%) than from the tannic acid treatments (29.2–50.0%). Therefore, we found that tannic acid was safe to use on rainbow trout eggs at concentrations of up to 200 mg/L for 15 min, but the control of bacteria was inferior to that provided by the standard iodine treatment.
Received May 10, 2011; accepted May 16, 2011
ACKNOWLEDGMENTS
We thank Wade Cavender and his staff for use of their laboratory for the bacteriology work, and we thank Cathryn Smith for data entry. The research was supported by the Utah Division of Wildlife and the Federal Aid in Sport Fish Restoration Program (Project F-74-R).