Oblique-angled, equilateral parallelogram. Often called a diamond.

Any of a series of slender curved bones articulated to the spine in pairs, serving to protect the thoracic cavity.

Barbel located between the upper and lower jaws, i.e., at or close to the corner of the mouth.

The gape or cleft of the mouth.

In morphology, an elongate, raised strip, margin or border on a bone, tooth, tissue membrane, etc.

Short, normally shallow stretch of fast-flowing, turbulent water in a stream; a small rapid; a rocky shoal or sandbar causing such a rapid.

Fissure in rock; a shallow or rocky place in a stream resulting in a riffle or rapid.

Narrow fissure or zone of faulting formed via tensional stress in the earth’s crust. When such forces are strong or prolonged enough to split the crust apart a central section will typically drop down or subside, sometimes forming a rift valley with steep walls as the gap widens. Water may become impounded in the valley, […]

Type of lake that forms in a rift zone or rift valley and often very deep with steep cliffs around the margins, also known as a rift valley lake, sag pond, or fault-trough lake. The largest freshwater lakes in the world are all of this type. Also used in the aquarium hobby in reference to […]

Generic term for any lake formed in a rift valley, but often used in specific reference to a group located in the East African rift, particularly those lying in its western and southern sections, i.e., the African Great Lakes. In the aquarium hobby the meaning of the term is typically restricted even further to include […]

Small stream.

Of, inhabiting, or located on the bank of a river or other watercourse, e.g., riparian vegetation.

Vaguely-defined, generic term for a variably-sized, natural, usually freshwater, watercourse, that empties into an ocean, sea, lake, or another river.

Total geographic area drained by a river plus all its tributaries.

Home-made device used to achieve uni-directional flow in an aquarium when inhabitants naturally occur in high-velocity rivers and streams. Typically, one or more powerheads are located at one end of the aquarium with intakes at the opposite end, these being connected via pipework located under the substrate. Though certainly beneficial, this should not be considered […]

Of, relating to, or situated on a river or riverbank.

Having irregular streaks.

Small stream or brook.

Abbreviation for ribonucleic acid, a single-stranded, self-replicating genetic material comprised of a chain of nucleotides. Present in nearly all living organisms, and replaces and performs the role of DNA in some viruses. Particularly important in protein synthesis and sometimes in transmission of genetic information.

Strong; vigorous; sturdy. Often used to describe the general body form of a fish.