Efficacy of formalin and povidone-iodine disinfection techniques on the eggs of three marine finfish species

Abstract

Surface disinfection trials were performed on eggs from three marine finfish species: California yellowtail (CYT; Seriola lalandi), white seabass (WSB; Atractoscion nobilis) and California halibut (HA; Paralichthys californicus). All three species were spawned from captive populations maintained at the Hubbs‐SeaWorld Research Institute (HSWRI). Five disinfection treatments were used for each species; Treatment 1 included 100 mg L−1 of formalin (F100) for 60 min (current HSWRI treatment), Treatment 2 included 1000 mg L−1 of formalin for 15 min (F1000), Treatment 3 included povidone–iodine of 50 mg L−1 for 15 min (PI50), Treatment 4 included povidone‐iodine of 100 mg L−1 for 10 min (PI100) and Treatment 5 involved a control with no chemical treatment (CONT). For each treatment, the per cent egg hatching rate, per cent survival to first feeding and notochord length at the time of hatching to the nearest 0.1 mm were recorded. Bacteria were also cultured from eggs after treatment to determine the effectiveness of each treatment in reducing the bacterial counts (CFU mL−1). Treatments F100, F1000 and CONT yielded the highest hatch rates for each species (70–80%), whereas treatments PI50 and PI100 yielded the lowest hatch rates (0–2%). There were no significant differences in survival to first feeding or notochord length, which suggests that the disinfection treatments did not have a negative effect on the yolk sac larvae. The PI50 and PI100 treatments had the lowest bacterial colony counts, showing almost zero bacterial growth. The highest bacterial growth occurred in the F100, F1000 and CONT treatments. Based on the results from this study, the F100 treatment provided the best balance of disinfection and larval health for CYT, WSB and HA.

Assessment of apparent effectiveness of chemical egg disinfectants for improved artificial hatching in Oreochromis karongae (Pisces: Cichlidae)

“…Therefore, egg disinfection against bacteria and fungi, is an important standard practice in artificial hatcheries. Egg disinfection prevents transfer of pathogens from broodstock to eggs [3].…”

Egg surface decontamination with bronopol increases larval survival of Nile tilapia, Oreochromis niloticus

“…6 CFU/g) were acceptable within the ranges of bacteria colonized on the surface of salmonid eggs (10 3 -10 6 CFU/g) (Austin 2006), however the viable counts in freshwater tilapia eggs taken in this study were higher than those in marine fish eggs. Treasurer et al (2005) reported the number of 3100 to 38 000 CFU/ml of egg in cod and haddock, while the colony counts in California yellowtail, white seabass, and California halibut were 16.7, 110.0, and 233.3 CFU/ml of egg, respectively (Stuart et al 2010). In our study, the bacterial counts (1.57 × 10 3 CFU/ml) in the hatchery water were comparable to those in the rearing system of California halibut (10 4 CFU/ml) (Stuart et al 2010) and of Mozambique tilapia (6.25 × 10 3 CFU/ml) (Subasinghe and Sommerville 1985).…”

“…Treasurer et al (2005) reported the number of 3100 to 38 000 CFU/ml of egg in cod and haddock, while the colony counts in California yellowtail, white seabass, and California halibut were 16.7, 110.0, and 233.3 CFU/ml of egg, respectively (Stuart et al 2010). In our study, the bacterial counts (1.57 × 10 3 CFU/ml) in the hatchery water were comparable to those in the rearing system of California halibut (10 4 CFU/ml) (Stuart et al 2010) and of Mozambique tilapia (6.25 × 10 3 CFU/ml) (Subasinghe and Sommerville 1985). The relatively high numbers of bacteria colonized on the surface of Nile tilapia eggs may be attributed to the rapid growth of the waterborne pathogens in temperate water temperature, particularly in the hatchery facility that is in the tropical region as Thailand, and the gelatinous matrix surrounding the eggs may be an appropriate substrate for bacterial proliferation.…”

“…A wide range of chemicals were reported as egg disinfectants for the routine use in fish hatcheries, e.g. benzalkonium chloride (Douillet and Holt 1994), glutaraldehyde (Salvesen and Vadstein 1995), formalin (Stuart et al 2010), hydrogen peroxide (Rach et al 1998;Rasowo et al 2007), iodine compounds (Salvesen and Vadstein 1995;El-Dakour et al 2013), and chlorine-based disinfectants such as sodium hypochlorite (Harboe et al 1994) and bronopol (Birkbeck et al 2006;Oono et al 2007). These disinfectants proved to be safe for different species of fish eggs, while highly toxic to aquatic pathogens.…”

Efecto de la acriflavina, formalina y glutaraldehído sobre la desinfección y la eclosión de los huevos del botete diana Sphoeroides annulatus

“…Actualmente, existen diversos productos químicos para desinfectar los huevos de peces, entre los que se encuentran el iodo, la formalina, la acriflavina y el glutaraldehído que han sido utilizados en especies marinas con resultados efectivos (Van Waters 1988, Salvesen et al 1997, Tucker 1998, Escaffre et al 2001, Katharios et al 2007, Ibarra-Castro 2008. En peces marinos, el iodo se ha aplicado para desinfectar huevos de diversas especies, y se ha observado su eficiencia en cuanto a la reducción de la carga bacteriana (Katharios et al 2007, Stuart et al 2010. La acriflavina se ha usado tradicionalmente para desinfectar huevos de peces marinos como es el caso del barramundi (Lates calcarifer), obteniendo resultados de eclosión mayores de 80% (Tucker 1998, Álvarez-Lajonchère & Tsuzuki 2008.…”