Marine Betta

Marine Betta: Care and Maintenance

The Marine Betta, known by its scientific name Calloplesiops altivelis, is an exquisite tropical longfin fish native to the waters of the Indian and Pacific Oceans. With their stunning appearance and unique hunting techniques, Marine Bettas make an excellent addition to saltwater aquariums. In this comprehensive guide, we will discuss everything you need to know about Marine Betta care and maintenance, including tank setup, water parameters, diet, tank mates, breeding, and more.

Species Overview

Marine Bettas, also known as Comets due to their flowing fins and striking patterns, can be found in the waters of East Africa to the central-Pacific south of Hawaii. They also span as far north as Japan and reach south to the Great Barrier Reef. Marine Bettas inhabit depths between 10 and 150 feet below the surface, sticking to pinnacle and lagoon patch reefs that provide ample hiding spots.

These slow-moving nocturnal predators are relatively shy and non-aggressive, spending most of their time hiding among rocks and coral. The Marine Betta’s unique natural adaptation allows it to mimic the appearance of the intimidating Moray Eel, helping them survive in the wild and adding a dazzling flourish to your tank.


Marine Bettas boast a dark brownish-black color, covered in white spots. Their pattern is so consistent that locating their actual eye can be difficult, as the iris is white, complementing their natural camouflage. However, the eyes are large, enabling the fish to see during their nighttime hunts.

The fish’s uniform coloration makes it difficult for potential predators to coordinate an attack. The Marine Betta’s large dot near their tail fin resembles an eye, further confusing predators and providing the fish with an opportunity to escape.

The outline of the spot near the tail fin and the edges of their other fins have a bright blue and orange color. The white dots transition to a pale blue tone near the dorsal and anal fins, which have vivid blue stripes.


While biologists are unsure about the lifespan of wild Marine Bettas, they can live for ten years or more in captivity. Once the fish is conditioned to feed, keeping them alive is simply a matter of maintaining low stress levels and optimal tank conditions.

Average Size

Marine Bettas can reach up to 8 inches long. Males are generally larger than females with slimmer bodies, but it can be difficult for even experienced fishkeepers to determine the fish’s sex.

Marine Betta Care

Marine Bettas are relatively easy to care for fish. While many veteran aquarists prize them for their beauty, they are also great fish for beginners due to their hardiness and low maintenance requirements.

Tank Size

Your Marine Betta requires a 55-gallon or larger tank due to its relatively large size. Simulating their natural environment requires enough room at the tank bed for the fish to roam and hunt. Keep the current low, as Comets are not active swimmers and spend most of their time lounging among rocks or serenely patrolling the bottom of the tank.

Water Parameters

Marine Bettas generally thrive in tanks once they adapt. Standard tropical conditions are acceptable. Maintain the following water parameters for optimal Marine Betta care:

  • Water temperature: 72 to 82°F
  • pH levels: 8.1 to 8.4
  • Water hardness: 8 to 12 dKH
  • Specific gravity: 1.020 to 1.025 sg

Tank Setup

Marine Bettas do best in tanks with plenty of live rock, as they prefer to spend their days hiding out due to their nocturnal nature. Position the rock pieces to allow the fish to explore while still providing adequate protection.

In addition to live rock, you can add caves, overhangs, and other hollow decorations that provide hiding space. Ensure these hiding spots are large enough to accommodate your Marine Betta’s size. These fish won’t disturb coral and are considered reef-safe.

When setting up the rock, ensure the large pieces are secure. The Marine Betta could dislodge loose rock as they explore, creating collapses that could crush them or other fish.

Common Possible Diseases

Marine Bettas are excellent beginner fish due to their resilience. Marine biologists speculate that the slime coating their bodies provides an anti-parasitic effect. Comets are so durable that they will survive a Cryptocaryon outbreak, which leads to marine ich, without ever contracting the disease. They generally recover from minor injuries without infection.

Food & Diet

As with all fish, it’s always recommended to ask the vendor what specific diet your Marine Betta was being fed in the shop. While some Comets are sold already conditioned to flakes or pellets, most aquarists find the fish prefer live or frozen seafood. The challenge is ensuring the Marine Betta gets its share of the food you provide to the tank community, as its unique hunting style means it won’t compete with more aggressive hunters for prey or prepared foods.

Presenting the food to them using a feeding stick is the best tactic. Waving the meal at the opening to their hiding spot tricks them into thinking the food is alive and entices them to dine. Over time, the Marine Betta will learn to accept the dead fish provided in the home tank.

If your Marine Betta comes conditioned to flakes or pellets, or you successfully wean them, opt for a carnivore blend. The scent of these foods will attract the Comet, and the pellets sink to the tank floor, which is the fish’s natural hunting ground.

Other aquarists have reported success in providing live black worms or mollies. Your Marine Betta will eat any small crustacean or fish that fits in its mouth. Timing your feedings at night or when you switch off the aquarium lamp can maximize your success because this is when the fish is naturally adapted to eat.

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Behavior & Temperament

Unlike the aggressive freshwater Betta or Siamese Fighting Fish, Marine Bettas are shy and docile. They generally won’t interact with other fish, preferring to spend their time alone on the floor of your tank.

Aquascaping your tank to position hiding spots that are still viewable will maximize your ability to enjoy these stunning fish. You can keep more than one Marine Betta, but males will fight if there isn’t enough space. Experts suggest a 6-foot or longer tank is necessary to provide adequate territory for multiple males.

Marine Betta Tank Mates

Marine Bettas are reserved and avoid other fish. Their size keeps them safe from comparable-sized predators, but they may become reclusive with aggressive fish and fail to compete for food. They usually do well with any common community fish or peaceful predators.

Suitable tank mates include:

  • Angelfish
  • Basslets
  • Butterflyfish
  • Damselfish
  • Engineer Gobies
  • Harlequin Tuskfish
  • Hawkfish
  • Shrimp and crabs that are too large to eat
  • Small Lionfish
  • Starfish
  • Tangs
  • Wrasses

Avoid smaller fish, as the Marine Betta can eat anything that fits in its mouth, including crustaceans.


Though breeding fish is always challenging, Marine Bettas are on the moderate end of the spectrum, further bolstering their value as excellent starter fish. You can house an opposite-sex pair or harem. However, you will need a 75-gallon or larger tank for two Marine Bettas and a 125-gallon or larger tank for a group.

Marine Bettas are hermaphroditic. Depending on their sexes at the time of purchase, the dominant fish will become male while the others gradually transition to female. Adult males will be aggressive toward each other. It’s generally best to purchase females or young Marine Bettas, as sorting out the social structure will be smoother and ensure all the Bettas survive.

It’s best to utilize a breeding tank if you plan to spawn Marine Bettas. Once fertilized, the female will lay 500 to 1,000 eggs on a cave wall. The male then guards them until they hatch. The process can take up to two weeks, but eggs usually hatch within five or six days.

Baby Marine Bettas feed on rotifers and microscopic foods during their first few days. After a week, they are large enough to eat live brine shrimp. You can also begin them on pellets and flakes, conditioning them to a feeding routine. Young Marine Bettas resemble adults, except for a white spot at their tail fin. Their coloration shifts into the darker tones of adulthood as they mature.


The Marine Betta is a beautiful and hardy fish species that makes an excellent addition to saltwater aquariums. With proper care and maintenance, these fish can thrive in captivity, providing a stunning visual display for aquarists of all experience levels. By following the guidelines outlined in this comprehensive guide, you can ensure a healthy and happy life for your Marine Betta. So, are you considering adding a Comet to your aquarium or already have one? Share your story and let us know how it went!

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