In ichthyology, scaleless or smooth skin.

In zoological nomenclature, the biological type (normally either a genus, species, or specimen) that determines how a name is applied.

Small aquarium of arguable definition. Freshwater nano-aquaria are generally accepted to hold between 5-10 US gallons (4.16-8.32 UK gallons; 18.93-37.85 litres) whereas in the marine hobby any aquarium with a volume of 30 US gallons (24.98 UK gallons; 113.56 litres) is generally considered to be a nano-system. These definitions vary, however. Also known as a […]

See nano aquarium.

In fishes, the part of the dorsal surface between the posterior edge of the skull and dorsal fin insertion.

External opening in the nasal cavity; a nostril.

Of, relating to, or located close to the nares.

Section of the cephalic lateral line canal anterior to the eyes.

Fleshy flap covering or partly covering the nostrils.

Flap of tissue inside the nostril.

Of or relating to the place or time of an orgamism's birth.

Floating on or swimmin in water.

Originating in a specific place or area; living or growing naturally in a particular region; indigenous.

Species occurring in a given region or ecosystem only as a result of natural processes, with no human intervention.

Term introduced by Charles Darwin referring to the nonrandom mechanism of evolution by which certain biological traits become either more or less common in a population due to differential, environmentally-influenced reproduction. Better-adapted individuals tend to produce more offspring, thus the population evolves, and this process can result in populations that gradually become specialised to inhabit […]

Used in reference to an exotic species that has become successfully established in nature outside of its native range.

Plural of nauplius.

First larval stage in certain crustaceans, comprising an unsegmented body with three pairs of appendages. Important constituent of plankton and the diet of some fishes.

Feeding on carrion.

Death of cells or tissue due to disease, injury, or interruption in blood supply.