The Free Online Aquaculture Dictionary

Z

Zeiformes

Order of fish (part of the superorder Acanthopterygii) includes fish such as John Dory (Zeus)

Zenith

The peak or highest level attainable. Opposite = Nadir

Zeolite

See ion exchange 

Zinc


Metal. Used extensively to galvanise iron to protect against rust (see corrosion). Can be toxic to fish if present in sufficient concentrations in it's free form, however this is only usually in very poorly buffered, acidic (pH<5.5)  solutions. 

Zoea

First larval stage of some decapod crustaceans (e.g. prawns and crabs), free swimming. 

Zooplankton

The animal component of plankton, consisting mainly of protozoa, rotifers, fish and insect larvae/eggs, small crustaceans. Usually existing in unison with phytoplankton which provide the basic food source for the primary consumer portion of the zooplankton. Other zooplankton are secondary consumers, preying on other zooplankton

Zoonose

A term used to describe a disease or pathogen that also effects man

Zoothanthellae

Species of algae which live in the tissues of some clam species such as tridachnids (the giant clams). See symbiosis for more detail 

Zoug Jar

Up-welling, conical based container for incubating eggs. The flow of water up through the eggs keeps them slightly fluidised, and theoretically provides clean water to all eggs. In practice, channeling can occur, brought about by the build up of fungus clumps, which, if left untreated, can soon spread. Zoug jars are therefore best for holding eyed eggs which are less prone to fungal attacks. Some species such as cyprinids can be hatched in Zoug jars. The use of Zoug jars or cylinder type incubators with large eggs such as salmonids, have been associated with malformations. This is thought to be due to a mixture of poor flow patterns as a result of jar design, causing localised low dissolved oxygen concentrations (see also piggy eyes)

Zygote

Cell formed by the union of the sperm and the egg.

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