- Skin with mucus gland. Paired fins made of rays and spines, or lobed fins lacking the rays and spines.
- Various types of scales (ctenoid, ganoid, or cycloid).
- Marine and fresh water species.
- Gills used for respiration.
- External fertilization: spawning, oviparous.
- No external ears.
- No eyes.
- Skeleton made of bone.
- Lateral line.
- Two chambered heart. Operculum covering the gills. Brain with large optic lobes and cerebellum.
- For example, Labeo, Hippocampus.