The X-ray tetra, scientifically known as the pristella maxillaris, is a small schooling fish naturally found in Brazil, Guiana, Guyana and Venezuela. They have a silver body with a red tail, and black-and-yellow striped ... More » Pets & Animals Marine Life Fish

According to NASA, Planet X does not exist, so there are no facts about it. As of 2015, the space agency's Wide-Field Infrared Survey Explorer, or WISE, found no evidence of a large, undiscovered planet within the solar ... More »

"Generation X" is the term used to describe individuals who were born between the early 1960s and the late 1970s or early 1980s. People from this era were once known as the "baby bust" generation. This is because the bir... More »

Von Rio tetras are small freshwater fish native to Rio de Janeiro in Brazil and commonly kept in aquariums. They are members of the family Characidae and the species Hyphessobrycon flammeus. Von Rio tetras are also known... More » Pets & Animals Marine Life Fish

One type of fish that starts with the letter "X" is the X-ray Tetra, known for its translucent skin that makes its backbone visible, according to OneKind, an animal protection charity. The fish also is called the Golden ... More »

Tetra GloFish are patented, genetically modified fish of the species Gymnocorymbus ternetzi. They are known as black or white skirt tetras in their natural form. GloFish also come in the species Danio rerio, or zebrafish... More » Pets & Animals Marine Life Fish

The bucktooth tetra is a freshwater fish of the characin family. It is notable for its bright red dorsal fin and two distinct black spots on its body. More » Pets & Animals Marine Life Fish