Found, appearing or present everywhere.
Invisible, continuous spectrum of light having a wavelength just shorter than the violet end of the visible spectrum but longer than that of x-rays.
Glossary: ultraviolet steriliser
Used toÂ kill bacteria in the water column by exposing it to ultraviolet light.
Plural of unculus.
Horny projection originating from a single cell of the epidermis found on the disc of Garra sp. and catfishes of the family Sisoridae, for example.
Glossary: undergravel filter
A filter which works by drawing water down through the substrate, where the cycle bacteria colonies are located, before returning it to the aquarium. Difficult to keep clean and now considered old fashioned.
To move in a smooth, wavelike motion; possessing a wavelike appearance or form.
Moving in a smooth, wavelike fashion.
Having a single point or cusp. Commonly used in reference to teeth of such form.
Scentific name comprising a single word, used for taxa higher than genus.
Fish species of which all individuals are the same gender.
Glossary: unpaired fins
The dorsal, caudal, anal and, if present, adipose fins.
Of, relating to, or denoting both the urinary and genital organs.
Glossary: urogenital duct
Tube draining the urogenital organs.
Glossary: urogenital papilla
See genital papilla.
Upturned, posterior tip or backwardly-orientated process of the lower vertebral column, generally comprised of fused vertebrae; series of bones articulating with the last true vertebra; usually included when counting vertebrae.
Abbreviation of ultraviolet.