482 FISH HATCHERY MANAGEMENT 



Fungus Disease See Saprolegniasis. 



Furuncle A localized infection of skin or subcutaneous tissue which 



develops a solitary abscess that may or may not drain externally. 

 Furunculosis A bacterial disease caused by Aeromonas salmonicida and 



characterized by the appearance of furuncles. 



Gall Bladder The body vessel containing bile. 



Gametes Sexual cells: eggs and sperm. 



Gape The opening of the mouth. 



Gas Bladder See Air Bladder. 



Gas Bubble Disease Gas embolism in various organs and cavities of the 

 fish, caused by supersaturation of gas (mainly nitrogen) in the blood. 



Gastric Relating to the stomach. 



Gastritis Inflammation of the stomach. 



Gastroenteritis Inflammation of the mucosa of the stomach and intes- 

 tines. 



Gene The unit of inheritance. Genes are located at fixed loci in chromo- 

 somes and can exist in a series of alternative forms called alleles. 



Genetic Dominant Character donated by one parent that masks in the 

 progeny the recessive character derived from the other parent. 



Genetics The science of heredity and variation. 



Genital Pertaining to the reproductive organs. 



Genus A unit of scientific classification that includes one or several 

 closely related species. The scientific name for each organism includes 

 designations for genus and species. 



Geographic Distribution The geographic areas in which a condition or 

 organism is known to occur. 



Germinal Disc The disc-like area of an egg yolk on which cell segmen- 

 tation first appears. 



Gill Arch The U-shaped cartilage that supports the gill filaments. 



Gill Clefts (Gill Slits) Spaces between the gills connecting the phar- 

 yngeal cavity with the gill chamber. 



Gill Cover The flap- like cover of the gill and gill chamber; the opercu- 

 lum. 



Gill Disease See Bacterial Gill Disease; Environmental Gill Disease. 



Gill Filament The slender, delicate, fringe-like structure composing the 

 gill. 



Gill Lamellae The subdivisions of a gill filament where most gas and 

 some mineral exchanges occur between blood and the outside water. 



Gill Openings The external openings of the gill chambers, defined by 

 the operculum. 



Gill Rakers A series of bony appendages, variously arranged along the 

 anterior and often the posterior edges of the gill arches. 



