Glass Cardinal

Also known as Glass Cardinalfish, Transparent Cardinalfish

The Glass Cardinal is a delicate and visually captivating species recognized for its semi-transparent body and soft silvery sheen, which gives it a distinctive “glass-like” appearance under aquarium lighting. Subtle internal structures and fine skeletal details can often be seen, creating an elegant and ethereal presence in reef aquariums. Peaceful, shy, and graceful, this species is an excellent choice for aquarists seeking a refined, low-key fish that complements calm community reef systems.

While hardy once established, the Glass Cardinal’s gentle nature and sensitivity to stress mean it thrives best in quiet, well-planned aquariums with patient care.

Key Features

• Scientific Name: Apogon leptacanthus
• Common Names: Glass Cardinalfish, Transparent Cardinalfish
• Adult Size: Up to 3 inches
• Lifespan: 3–5 years with proper care
• Temperament: Peaceful, shy, and non-aggressive
• Reef Compatibility: Completely reef safe; will not harm corals or invertebrates
• Minimum Tank Size: 30 gallons minimum; 40+ gallons recommended for groups
• Experience Level: Intermediate; easy to maintain but sensitive during acclimation

Habitat & Tank Requirements

Tank Environment:
The Glass Cardinal prefers calm, sheltered reef environments with abundant live rock, caves, crevices, and shaded areas. This species spends much of the day hovering near rock structures or retreating into cover, becoming more active during low-light periods and feeding times. Bright, open aquariums without adequate hiding places may cause prolonged stress and excessive hiding.

Gentle water movement and a peaceful setting are essential, as this species does not tolerate aggressive tank mates or constant disturbance.

Water Parameters:

• Temperature: 72–78°F (22–26°C)
• Salinity: 1.020–1.025
• pH: 8.1–8.4
• Stable reef conditions are critical for long-term health

Equipment Recommendations:

• Standard reef-quality filtration
• Protein skimmer
• Gentle to moderate water circulation (avoid strong or direct flow)

Maintaining stable water quality and a stress-free environment is key to success with this species.

Diet & Feeding

Glass Cardinals are carnivores that feed on small zooplankton in the wild. Wild-caught individuals may be hesitant feeders initially and require patience during acclimation.

Recommended Foods:

• Frozen Foods: Mysis shrimp, enriched brine shrimp, cyclops, copepods, finely chopped seafood
• Staple Foods: High-quality marine pellets or micro-pellets (once acclimated)
• Live Foods: Live brine shrimp or copepods may be helpful during initial feeding response

Feeding Frequency:

• Once or twice daily
• Smaller, frequent feedings are preferred

Special Note:
Due to their shy and slow-feeding nature, ensure food reaches them before faster or more aggressive fish consume it.

Social Structure & Group Dynamics

• Natural Behavior: Shoaling species; best kept in small groups of 3–6 individuals
• Single Specimens: Can be kept singly but are more confident and active in groups
• Temperament: Completely peaceful and non-territorial
• Tank Mates: Best suited to calm, non-aggressive reef fish

Males are mouth-brooders, a characteristic shared with other cardinalfish species.

Notes & Considerations

• Semi-transparent body creates a unique glass-like appearance
• Subtle silver and faint iridescent highlights visible under aquarium lighting
• Peaceful and non-aggressive; ideal for tranquil reef systems
• Shy and may hide frequently during early acclimation
• Prefers dim to moderate lighting and gentle water movement
• Easily outcompeted by fast or aggressive feeders
• Best observed hovering near rockwork or during feeding times
• Requires patience during acclimation, especially with feeding
• Not recommended for highly active or aggressive community tanks
• Excellent choice for peaceful reef displays and species-focused aquariums

Why Choose a Quarantined Glass Cardinal?

Purchasing a quarantined Glass Cardinal from us means you are starting with a healthier, better-acclimated fish. All specimens are carefully observed, treated when necessary, and monitored for feeding response before sale. Our quarantine process is especially valuable for this shy, wild-caught species, greatly improving acclimation success and long-term survival in the home aquarium.