Evaluation of Formalin and Hydrogen Peroxide Treatment Regimes on Rainbow Trout Eyed Eggs

Abstract

This study examined the use of antifungal chemicals at nonstandard treatment concentrations or treatment intervals during the incubation of eyed eggs of rainbow trout Oncorhynchus mykiss until hatch in vertically stacked incubation trays. Daily chemical treatments of 500, 1,000, and 1,667 mg of commercial formalin (containing 37% formaldehyde)/L for 15 min and a nonchemical, dead-egg-removal control were included in three trials. The second and third trials added a true control (no antifungal measures) and the third trial also incorporated a treatment of formalin at 1,667 mg/L for 15 min every other day. In these three trials, formalin at 1,000 or 1,667 mg/L daily or 1,667 mg/L every other day significantly improved egg survival to hatch relative to the other treatments and completely controlled fungal growth. A fourth trial evaluated treatments of formalin at 750 mg/L for 15 min daily or every other day, hydrogen peroxide at 500 mg/ L for 15 min daily or every other day, and control groups for both treatments. Egg survival to hatch was significantly different among the treatments; the daily 750-mg/L formalin treatment produced the greatest number of hatched fry, followed by the treatment with 750 mg/L formalin every other day, the dead-egg-removal control, and daily hydrogen peroxide treatment. Survival in the every-other-day hydrogen peroxide treatment and the true control could only be estimated because of extreme fungal growth, and was substantially less than the other treatments. Only daily 750 mg/L formalin treatments and dead egg removal completely controlled fungal growth. To adequately control fungus and maximize egg survival, either daily 15-min treatments of formalin at concentrations of at least 750 mg/L or every-otherday treatments of formalin at 1,667 mg/L are recommended.

The in vitro antifungal activity of 30 Chinese herb extracts to Saprolegnia sp.

“…With restrictions on the use of malachite green, more emphasis has been directed toward identifying suitable alternatives. Alternative antifungal agents have focused mainly on three candidates: formalin (Barnes and Soupir, 2006;Akpoilih and Adebayo, 2010), hydrogen peroxide (Rach et al, 2004;Mitchell et al, 2009;Matthews et al, 2012), and sodium chloride or seawater (Waterstrat and Marking, 1995;Koeypudsa et al, 2005;Ali, 2009). Formalin is widely used as a topical treatment for saprolegniosis; however, it has the potential of being toxic, particularly at temperatures above 25°C (Akpoilih and Adebayo, 2010) and reported dosages of 50-150 mg L À1 (Barnes and Soupir, 2006;Akpoilih and Adebayo, 2010), and is impractical for use in large ponds.…”

Suppression ofSaprolegniainfections in rainbow trout (Oncorhynchus mykiss) eggs using protective bacteria and ultraviolet irradiation of the hatchery water

“…No prophylactic formalin treatment was applied, because in February 2006 (the time of the experiment) this practice was not encouraged by National Veterinary and Food Research Institute (EELA, from May 2006 onwards Finnish Food Safety Authority EVIRA) and the FGFRI complied with this recommendation. Formalin baths decreased egg mortality compared to the control and the UV0 groups treated with protective bacteria, but the mortality (81.8% AE 10.6%) was still extremely high compared to results of Schreier et al (1996) and Barnes and Soupir (2007). Most likely, more frequent formalin treatments started after the incubation of the eggs would have resulted in lower egg mortality (Barnes & Soupir 2007).…”

“…Formalin baths decreased egg mortality compared to the control and the UV0 groups treated with protective bacteria, but the mortality (81.8% ± 10.6%) was still extremely high compared to results of Schreier et al . () and Barnes and Soupir (). Most likely, more frequent formalin treatments started after the incubation of the eggs would have resulted in lower egg mortality (Barnes & Soupir ).…”

“…() and Barnes and Soupir (). Most likely, more frequent formalin treatments started after the incubation of the eggs would have resulted in lower egg mortality (Barnes & Soupir ).…”

Evaluation of oxidative stress markers in the heart and liver of rainbow trout (Oncorhynchus mykiss walbaum) exposed to the formalin

“…Eggs treated three times daily with 100 ppm formalin had the highest ( p  < 0.05) percentage of hatched eggs (Small and Chatakondi 2006). Barnes and Soupir (2007) have recommended either daily 15-min formalin treatments at concentrations of at least 750 mg/L or every-other-day treatments at 1667 mg/L to adequately control fungus and maximize rainbow trout egg survival. Wagner et al (2008) have compared the bactericidal ability of four common disinfectants (formalin, iodine, rock salt, and hydrogen peroxide) in vivo on rainbow trout eggs.…”