Fish Hatchery Management - fisheries & aquaculture

FISH HE,AI,'IH MANAGEMT]N1 341oxygen usually provide room for expansion. A general precaution is to usea double bag system, one bag filled and sealed within another. It is best toship a minimum number of specimens. Sick flsh and coldwater fish, such astrout, require greater volumes of water than healthy or warmwater fish.Twenty volumes of water for each volume of fish usually will be adequatefor healthy fish, but greater volumes should be provided for sick fish. Duringextreme hot or cold weather, insulated containers may be required.Expanded polystyrene picnic hampers provide good insulation but are relativelyfragile and require protection against damage. They should bepacked, therefore, in a protective corrugated cardboard box or other container.Coldwater fish usually ship better if ice is provided. The ice shouldbe packed in double plastic bags so that it will not leak when it melts.S hipping Preseraed SpecimensPreservatives typically are corrosive and odorous' Containers should be unbreakableand absorbent material should be provided in the event leakagedoes occurs. A good procedure is to fix the fish in a proper fixative for aday or two, then place the preserved fish, with a very small volume of fixative,in a plastic bag. The sealed bag should be placed within a secondplastic bag, which also should be sealed. This durable package has minimalweight. Select representative specimens. Examine them carefully to supplydata in the order given in the Diagnostic Summary Information form.Bouin's solution is a preferred fixative. Its recipe is: picric acid(da.rgero.rs), 17.2 grams; distilled water, 1,430 milliliters; formalin, 475 milliliters;glacial acetic acid, 95 milliliters. NOTE: picric acid explodes whenrapidly heated. Handle accordingly. Weigh picric acid and place crystals ina pyrex container large enough to hold 2 liters (2,000 milliliters) and adddistilled water. Heat on a stove. Stir occasionally until all crystals are dissolved.Do not boil the solution. When crystals have dissolved, remove thesolution from the stove and cool it completely. Add the formalin and glacialacetic acid to the cooled solution. Stir briefly and pour the mixtureinto a jar. This solution will keep well, but should be protected fromfreezing.Volume of the fixative should be at least five to ten times that of thefish or tissue. (Thus, put only one 6-inch fish in a pint of fixative.) Fishand tissues should be left in the fixative for at least 24 hours, and then thefixing solution replaced with 65(/0 ethyl alcohol. However, if alcohol is notavailable, retain the specimens in Bouin's fluid.To facilitate fixation, fish, regardless of size, should be slit down the abdomenfrom the anus to the gills. The air bladder should be pulled out andbroken to permit fixation of the kidney. The kidney of 6-inch or larger fishshould be split along its entire length. The intestines and other organs