Use of Formalin Treatments During Incubation of Eyed Eggs of Brown Trout
M.E. Barnes, W.A. Sayler, R.J. Cordes-2001
North American Journal of Aquaculture, 63(4): 333-337
Abstract:
To test the efficacy of formalin in controlling the
fungus Saprolegnia, we administered daily formalin treatments (1,667
mg/L for 15 min) to embryos (eyed eggs to hatch) of brown trout Salmo
trutta and compared their survival with that of untreated embryos. The
study was conducted each year from 1996 to 1998. In all 3 years, embryo
survival to hatch in both groups was greater than 90%. Survival to hatch was
not significantly improved in the treated trays of eggs compared with the
untreated trays, where dead eggs were manually removed for Saprolegnia
control. Both formalin treatments and hand-picking of dead eggs adequately
controlled visible fungal development. Although not essential for fungal
control, formalin treatments on high-quality brown trout eggs from the eyed
stage of embryo development through hatch are recommended to provide
reductions in hatchery labor, but only if they can be administered safely.
(South Dakota Department of Game, Fish, and Parks,
McNenny State Fish Hatchery, Rural Route 1, Box 205, Spearfish, South Dakota
57783-8905, USA)