Marine Betta

Also known as the Comet or Calloplesiops

The Marine Betta is a stunning and unusual species that brings dramatic finnage and mesmerizing mimicry to marine aquariums. Native to the Indo-Pacific region, from the Red Sea to Samoa and French Polynesia, this distinctive predator features a dark body adorned with white spots and an elaborate false eye spot on its dorsal fin that mimics a moray eel. With their shy temperament, impressive size, and specialized requirements, Marine Bettas make fascinating additions for intermediate to advanced aquarists with appropriate cave-rich systems and understanding of their unique behaviors.

Key Features

• Scientific Name: Calloplesiops altivelis
• Common Names: Marine Betta, Comet, Comet Grouper, Marine Comet
• Adult Size: 7–8 inches (18–20 cm); commonly 6–7 inches in aquariums
• Lifespan: 8–12 years with proper care
• Temperament: Shy and reclusive; predatory toward small fish
• Reef Compatibility: Reef-safe with caution – may consume small fish and shrimp
• Minimum Tank Size: 55 gallons minimum (75+ gallons recommended)
• Experience Level: Intermediate to Advanced – requires patience and proper environment

Habitat & Tank Requirements

Natural Habitat: Found on coral reefs, rocky areas, and caves at depths of 3–150 feet. Inhabits deep crevices and caves, emerging at dusk to hunt.

Tank Environment:

• Multiple caves and deep crevices essential
• Large hiding spots to accommodate full body
• Subdued to moderate lighting strongly preferred
• Low to moderate water flow
• Peaceful to semi-aggressive tankmates
• Compatible with reef or FOWLR systems
• Secure lid recommended

Water Parameters:

• Temperature: 74–80°F (23–27°C)
• Salinity: 1.023–1.025 specific gravity
• pH: 8.1–8.4
• Ammonia/Nitrite: 0 ppm
• Nitrate: <20 ppm
• Alkalinity: 8–12 dKH

Diet & Feeding

Recommended Foods:

• Fresh/frozen shrimp, fish, krill, squid (primary diet)
• Silversides, chopped seafood
• Live feeder fish or shrimp (helpful during acclimation, quarantined)
• Marine carnivore pellets (once established)
• Varied meaty diet essential

Feeding Schedule:

• Feed 3–4 times weekly for adults
• Juveniles require daily feeding
• Often feeds only at dusk or in subdued lighting initially
• May require patience to establish feeding
• Use feeding tongs or stick
• Remove uneaten food promptly

Behavior & Compatibility

Tank Mates:

• Compatible with: Large tangs (6+ inches), large angelfish, large wrasses, triggerfish, pufferfish, lionfish, groupers, peaceful to semi-aggressive fish
• Caution with: Fish 3–5 inches (may be consumed once Marine Betta is established), aggressive species that may harass
• Avoid: All small fish (under 3 inches), ornamental shrimp, small crabs, very aggressive species

Social Behavior:

• Extremely shy and reclusive, especially initially
• Spends most time hiding in caves
• Primarily nocturnal; most active at dusk and night
• Predatory toward fish small enough to swallow
• Best kept as single specimen
• May take weeks to become comfortable and visible
• Displays false eyespot when threatened (mimics moray eel head)
• Becomes bolder once established but remains cave-dwelling

Defensive Mimicry: When threatened, the Marine Betta positions its dorsal fin to display a large false eye spot while hiding its head, creating the appearance of a moray eel’s head. This remarkable defensive behavior deters predators.

Reef Compatibility: Reef-safe with corals and anemones; completely safe with sessile invertebrates. May consume small ornamental shrimp and small fish (under 3 inches). Generally safe with larger cleaner shrimp. Will not harm corals.

Color & Development

Coloration: Deep brown to black body covered with small white to blue-white spots creating starry appearance; elaborate flowing fins; prominent false eye spot (ocellus) on dorsal fin rimmed in white; fins edged in white or blue; absolutely stunning when fully displayed.

Color Intensity:

• High-quality diet maintains spot brightness
• Colors most vivid during displays or when threatened
• Stress may cause temporary darkening
• False eyespot remains prominent throughout life
• Excellent water quality preserves coloration
• Juveniles show same pattern as adults

Size & Growth:

• Juveniles typically available at 3–4 inches
• Moderate growth rate: 2–3 inches annually
• Reach 6–7 inches within 2–3 years
• Growth slows after reaching 6 inches

Why Choose a Quarantined Marine Betta?

A properly quarantined Marine Betta is a healthier, acclimated specimen that has been observed, treated, and conditioned for aquarium life. Our quarantine protocol includes 4–6 weeks minimum observation (critical for shy species), preventative parasite treatment, dietary conditioning to frozen foods (most important factor), feeding behavior verification, and stress reduction with appropriate cave structures.

These spectacular fish combine dramatic flowing fins with unique moray eel mimicry and stunning spotted patterns, making them captivating additions for patient aquarists. Their shy nature means sightings feel rewarding, and their defensive display behavior is truly fascinating to observe. Perfect for aquarists who appreciate reclusive species and can provide cave-rich environments with subdued lighting. Not ideal for those wanting a constantly visible centerpiece, but exceptional for dedicated aquarists who value unique behaviors and are willing to work with their nocturnal, cave-dwelling nature. A true conversation piece that rewards patience with glimpses of remarkable beauty and behavior.