Glossary of Hatchery terms

Glossary of Hatchery Feed Terms - C - D

October 9, 2019


Carotenoids — Pigment molecules found in algal cells and crustaceans (exoskeleton) as well as in plant and animal fats. Fed to fish, salmonids in particular.
Copepod — A major group of minute crustaceans common to freshwater and saltwater. They have no carapace and have a single median eye. Some are free-swimming and belong to the zooplankton, while others are parasitic on the skin and gills of fish.

Copepodite — Developmental stage of copepods after the nauplius stage.

Crumbles — Granular processed fish feed made by crushing pellets between rollers moving at different speeds; the resulting pellet fragments are screened to produce several size ranges of particles.

Crustacean — Aquatic animal belonging to the phylum Arthropoda, a major group of invertebrate organisms characterized by their chitinous exoskeleton and jointed appendages, occurring in marine and freshwaters and on land, e.g. crabs, lobsters, crayfish, shrimps, prawns, etc. Microcrustaceans include cladocerans and copepods.

Cyst — (a) The resilient non-mobile, dehydrated, resistant, inactive, dormant stage of a free-living or parasitic organism, as a response to adverse environmental conditions.  (b) A non-living membrane enclosing a cell or cells.


Decapsulation — A process whereby the capsules of brine shrimp cysts are removed before they are used further in cultivation. The cyst, often called an egg, is an arrested gastrula encapsulated within a hard lipoproteinaceous shell or capsule.

Die — In mechanics: a piece of metal with holes through it, used in extruding pellets.

Diet, purified — A feed made out of refined ingredients with specified analyses; used for nutritional research only.

Diet, reference (RD) — In nutrition research: a diet with which one can compare response to experimental design and dietary treatments.

Diet, standard reference (SRD) — In nutrition research: a precisely defined and reproducible test diet satisfying the nutritional needs of fish for use in feeding studies to facilitate comparisons betxween various experiments, species, locations, researchers and other factors and conditions.

Diet, supplemental —  A prepared diet formulated to provide additional nutrients to those obtained from natural food organisms grown in the culture environment (usually ponds). It may be undiluted as a supplement to other feeds, offered free choice with other parts of the diet separately available, or mixed with other feed ingredients to produce a complete feed.

Digestion coefficient, true (TDC) — Digestion efficiency expressed as the ratio of total weight of feed consumed minus weight of excreted faecal matter minus weight of metabolic faecal nutrient excreted over total weight of feed consumed.