GLOSSARY 487 



Length May refer to the total length, fork length, or standard length 



(see under each item). 

 Lesion Any visible alteration in the normal structure of organs, tissues, 



or cells. 

 Leucocyte A white blood corpuscle. 



Lime (Calcium Oxide, Quicklime, Burnt Lime) CaO; used as a disinfec- 

 tant for fish-holding facilities. Produces heat and extreme alkaline 



conditions. 

 Line Breeding Mating individuals so that their descendants will be 



kept closely related to an ancestor that is regarded as unusually desir- 

 able. 

 Linolenic Acid An 18-carbon fatty acid with two double bonds. Certain 



members of the series are essential for health, growth, and survival of 



some, if not most, fishes. 

 Lipid Any of a group of organic compounds consisting of the fats and 



other substances of similar properties. They are insoluble in water, but 



soluble in fat solvents and alcohol. 

 Long Bath A type of bath frequently used in ponds. Low concentrations 



of chemical are applied and allowed to disperse by natural processes. 

 Lymphocystis Disease A virus disease of the skin and fins affecting 



many freshwater and marine fishes of the world. The disease is caused 



by the lymphocystis virus of the Iridovirus group. 



Malignant Progressive growth of certain tumors that may spread to dis- 

 tant sites or invade surrounding tissue and kill the host. 



Malnutrition Faulty or inadequate nutrition. 



Mandible Lower jaw. 



MAS See Motile Aeromonas Septicemia. 



Mass Selection Selection of individuals from a general population for 

 use as parents in the next generation. 



Mating System Any of a number of schemes by which individuals are 

 assorted in pairs leading to sexual reproduction. 



Maxilla or Maxillary The hindmost bone of the upper jaw. 



Mean The arithmetic average of a series of observations. 



Mechanical Damage Extensive connective tisue proliferation, leading 

 to impaired growth and reproductive processes, caused by parasites 

 migrating through tissue. 



Median A value in a series halfway between the highest and lowest 

 values. 



Melanophore A black pigment cell; large numbers of these give fish a 

 dark color. 



Menadione A fat-soluble vitamin; a form of vitamin K. 



