Definition

Noun: 1. A small, brightly colored freshwater fish belonging to the family Rivulidae, found in small streams and bodies of water in tropical America. Many species are popular in the aquarium hobby. A notable biological characteristic of some rivulus species is that they are self-fertilizing hermaphrodites.

Usage Examples

• The rivulus is a fascinating subject for biologists studying hermaphroditism in vertebrates.
• Aquarists appreciate the rivulus for its vibrant colors and interesting behavior.
• Several species of rivulus are adapted to survive in temporary pools that dry up seasonally.

Advanced Usage

• The term is used specifically in ichthyology (the study of fish) and aquarium keeping. It typically refers to fish within the genus and related genera now classified under the family Rivulidae, which are often called "killifish."
• The most famous species is the mangrove rivulus (), often cited in scientific literature for its unique reproductive strategy.

Variants and Related Words

• Killifish (n): A common name for various small, often colorful fish in the families Cyprinodontidae, Fundulidae, and Rivulidae. Many rivulus species are referred to as killifish by aquarium enthusiasts.
• Cyprinodont (n): A member of the order Cyprinodontiformes, to which rivulus belong. This is a broader taxonomic classification.

Synonyms

• Killifish (in a general, non-scientific context)
• Cyprinodont (in a broad taxonomic context)

Related Idioms or Phrases

Noun

1. found in small streams of tropical America; often kept in aquariums; usually hermaphroditic