(a) Specifications. Formalin is an aqueous solution containing approximately 37 percent by weight of formaldehyde gas, U.S.P.
(b) Sponsors. See Nos. 049968, 050378, and 067188 in Sec. 510.600(c) of this chapter.
(c) [Reserved]
(d) Conditions of use. It is added to environmental water as follows:
(1) Indications for use. (i) Penaeid shrimp. For control of external protozoan parasites Bodo spp., Epistylis spp., and Zoothamnium spp.
(i) Penaeid shrimp. For control of external protozoan parasites Bodo spp., Epistylis spp., and Zoothamnium spp.
(ii) All finfish. For control of external protozoa Ichthyophthirius spp., Chilodonella spp., Ichthyobodo spp., Ambiphrya spp., Epistylis spp., and Trichodina spp., and monogenetic trematodes Cleidodiscus spp., Gyrodactylus spp., and Dactylogyrus spp.
(iii) All finfish eggs: For control of fungi of the family Saprolegniaceae.
(2) Amount. The drug concentrations required are as follows:
(i) For control of external protozoan parasites on shrimp: ------------------------------------------------------------------------
Concentration of formalin (microliters
per liter)
---------------------------------------
Shrimp Tanks and raceways
(up to 4 hours Earthen ponds
daily) (single treatment)------------------------------------------------------------------------Penaeid Shrimp.................. 50 to 100 \1\..... 25 \2\------------------------------------------------------------------------\1\ Treat for up to 4 hours daily. Treatment may be repeated daily until
parasite control is achieved. Use the lower concentration when the
tanks and raceways are heavily loaded.\2\ Single treatment. Treatment may be repeated in 5 to 10 days if
needed.
(ii) For control of external parasites on finfish: ------------------------------------------------------------------------
Administer in tanks and
raceways for up to 1 Administer in earthen
Aquatic species hour (microliter/liter ponds indefinitely
or part per million ([micro]L/L or ppm)
([micro]L/L or ppm))------------------------------------------------------------------------Salmon and trout:Above 50 [deg]F Up to 170 15 to 25 \1 2\Below 50 [deg]F Up to 250 15 to 25 \1 2\All other finfish Up to 250 15 to 25 \1 2\------------------------------------------------------------------------\1\ Use the lower concentration when ponds, tanks, or raceways are
heavily loaded with phytoplankton or fish to avoid oxygen depletion
due to the biological oxygen demand by decay of dead phytoplankton.
Alternatively, a higher concentration may be used if dissolved oxygen
is strictly monitored.\2\ Although the indicated concentrations are considered safe for cold
and warm water finfish, a small number of each lot or pond to be
treated should always be used to check for any unusual sensitivity to
formalin before proceeding.
(iii) For control of fungi of the family Saprolegniaceae on finfish eggs: Eggs of all finfish except Acipenseriformes, 1,000 to 2,000 [micro]L/L (ppm) for 15 minutes; eggs of Acipenseriformes, up to 1,500 [micro]L/L (ppm) for 15 minutes.
(3) Limitations. Fish tanks and raceways may be treated daily until parasite control is achieved. Pond treatment may be repeated in 5 to 10 days if needed. However, pond treatments for Ichthyophthirius should be made at 2-day intervals until control is achieved. Egg tanks may be treated as often as necessary to prevent growth of fungi. Do not use formalin which has been subjected to temperatures below 40 [deg]F, or allowed to freeze. Do not treat ponds containing striped bass. Treatments in tanks should never exceed 1 hour even if fish show no signs of stress. Do not apply formalin to ponds with water warmer than 27 [deg]C (80 [deg]F), when a heavy bloom of phytoplankton is present, or when the concentration of dissolved oxygen is less than 5 milligrams per liter. [51 FR 11441, Apr. 3, 1986, as amended at 58 FR 59169, Nov. 8, 1993; 59 FR 60076, Nov. 22, 1994; 63 FR 38304, July 16, 1998; 68 FR 5563; Feb. 4, 2003; 72 FR 45158, Aug. 13, 2007; 76 FR 17339, Mar. 29, 2011; 79 FR 2786, Jan. 16, 2014]