1. a small freshwater or brackish water fish often used in aquariums and scientific research

Examples

• The killifish adapted quickly to the changing water conditions.
• Scientists study killifish to understand aging processes.
• Many aquarium enthusiasts keep colorful killifish in their tanks.
• The killifish population thrived in the shallow pond.
• Researchers use killifish as model organisms in genetics studies.
• The pet store had several species of killifish for sale.