reef fish, saltwater
Glass Cardinalfish
Ambassis sp. (often Ambassis jacksoniensis or similar)
Small, elongated, and highly transparent body where the vertebral column and internal organs are visible. Large eyes relative to head size, two distinct dorsal fins, and a deeply forked tail. Often possesses a silvery or yellowish tint along the midline. Scales are thin and cycloid.
- Habitat
- Inhabits coastal waters, estuaries, and sheltered lagoon…
- Size & weight
- Typically reaches 4 to 10 cm in length.…
- Diet
- Opportunistic carnivore and planktivore.…
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Physical characteristics
Small, elongated, and highly transparent body where the vertebral column and internal organs are visible. Large eyes relative to head size, two distinct dorsal fins, and a deeply forked tail. Often possesses a silvery or yellowish tint along the midline. Scales are thin and cycloid.
Habitat & distribution
Inhabits coastal waters, estuaries, and sheltered lagoons. Often found in mangroves and seagrass beds in the Indo-Pacific and Australian regions, preferring depths of 0 to 5 meters.
Behavior
Highly social and gregarious; typically found in large, dense schools during the day to avoid predation. They are mainly nocturnal or crepuscular feeders.
Diet
Opportunistic carnivore and planktivore. Feeds mainly on zooplankton, small crustaceans (like copepods), and tiny aquatic insect larvae.
Reproduction
External spawners; females release eggs into the water column or near vegetation where they are fertilized by males. They have a relatively short life cycle with rapid development from larvae to juvenile.
Ecological role
Acts as a vital link in the food web, serving as primary prey for larger carnivorous fish, wading birds, and sea snakes. Help transfer energy from zooplankton to higher trophic levels.
Similar species
Glass Perchlets (Ambassidae) look similar but can be distinguished by their deep bodies and spine counts. Other transparent cardinalfish (Apogonidae) may have different fin positioning and dorsal spine lengths.
Identification tips
Look for the extreme transparency of the body, a silver-lined gut cavity, and the divided dorsal fin. In lagoons, they are often seen hovering in shimmering groups near structures or roots.
Interesting facts
Members of this genus are often called 'Glassies' due to their see-through nature. Their transparency is a form of camouflage called crypsis, making them difficult for predators to spot in the water column.
Field notes
From lagoon