Because fish feeds usually contain relatively high amounts of fish meal and/or fish oil, they are very susceptible to rancidity. In addition, ascorbic acid is highly volatile, but critical to normal growth and development of most species of fish.
should be stored in a cool, dry place and should never be kept on hand for more
than three months. Refrigeration of dry feeds is not recommended because of the
high moisture content of that environment. Freezing is an acceptable way of
extending the shelf life, however.
Vitamin C is an essential vitamin for fish, and most
species tested are not capable of synthesizing their own. Stabilized
(phosphorylated) forms of ascorbic acid are available and are used in many, but
not all, fish feeds. Feeds that do not contain stabilized ascorbic acid are not
recommended for fish. If assays for ascorbic acid content are to be run it is
imperative to know which form the vitamin is in before sending the feed sample
to a laboratory.