The Marine Betta (Calloplesiops altivelis) also sometimes called the Comet, is a stunning and unique saltwater fish with a mesmerizing starry pattern and an unmistakable false eye spot near its tail. This distinctive marking helps confuse both predators and prey, making it a fascinating species to observe. While Marine Bettas are predatory and will eat small fish and invertebrates, they are surprisingly shy and prefer peaceful tankmates that won’t harass them. When housed appropriately, they display slow, graceful swimming behavior, making them a captivating centerpiece for a well-planned aquarium.

 

General Habitat & Tank Requirements:

  • Tank Size: 50 Gallons or larger.
  • Aquascape: Provide plenty of caves, ledges, and overhangs using live rock. Hiding spots help reduce stress and encourage natural behavior.
  • Substrate: No specific substrate is required, and they adapt well to sand, crushed coral, or bare-bottom setups.
  • Lighting: Marine Bettas tend to be sensitive to bright light and may hide during the day in high light systems. 

Water Conditions:

  • Temperature: 75°F to 80°F (23°C to 27°C).
  • pH: 7.7 to 8.5.
  • Specific Gravity (Salinity): 1.020 to 1.026.
  • Water Quality: Maintain ammonia and nitrite levels at 0 ppm, and nitrates below 20 ppm.
  • Filtration: Employ high-quality filtration, such as a protein skimmer, to ensure optimal water quality.

Diet and Feeding

Marine Bettas are carnivorous predators that primarily feed on small fish and invertebrates. They prefer live or frozen foods and may take time to adjust to prepared diets.

  • Primary Diet: Live or Frozen Food. Mysis shrimp, krill, and silversides. They may also eat small live fish.
  • Feeding Tips: Feed 1-2 times per day in small portions. If offering frozen food, ensure it is fully thawed before feeding.

Behavior and Compatibility

Marine Bettas are predatory yet shy. They tend to avoid conflict but will eat smaller tank mates. Choose companions carefully.

Common Tank Mates: Larger peaceful fish like Tangs, wrasses, angelfish, and certain butterflyfish.

Tank Mates to Avoid: Small fish and invertebrates. Anything that fits in their mouth is at risk. Aggressive or fast-moving fish should also be avoided.

Coral Compatibility: While Marine Bettas aren't often kept in reef aquariums, they are generally considered safe with corals.

Behavioral Notes

  • Shy, but Predatory: They tend to hide in rock crevices but will ambush prey when hunting.
  • Unique Hunting Strategy: Their false eye spot confuses prey, making it difficult to detect their true head position.
  • Nighttime Activity: Marine Bettas tend to be most active in the hours when the lights are dim or off.

Heath and Maintenance

  • Water Changes: Regular 10-20% weekly or bi-weekly water changes help maintain good water quality.
  • Observation: Monitor for signs of disease or stress such as rapid breathing, not eating, or lesions on the body.
  • Quarantine: Always quarantine new additions to prevent disease introduction.