Any of numerous attractively coloured freshwater South American and African fishes (family Characidae), often kept in home aquariums. Tetras are small, lively, hardy, and unaggressive. The slender neon tetra (Paracheirodon, or Hyphessobrycon, innesi) has gleaming red hind parts and a neonlike blue-green stripe on its sides. The glowlight tetra (Hemigrammus erythrozonus) has a shining red stripe along each side. The body of the silver tetra (Ctenobrycon spilurus) is flattened sidewise.