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Marine Betta Fish: Care Guide, Pictures, Varieties, Lifespan & More

Brooke Billingsley

By Brooke Billingsley

a Marine Betta fish

If you’re looking for an addition to your reef tank, the Marine Betta fish may be just what you’re looking for. These eye-catching fish are also sometimes called Comets. They are reef-safe fish that sport an attractive camouflage pattern and lovely long fins. The Marine Betta can add a unique element to your saltwater tank, but they are shy fish with particular needs to keep them happy and healthy.


Quick Facts about Marine Betta

Species Name: Calloplesiops altivelis
Family: Plesiopidae
Care Level: Moderate
Temperature: 72–81˚F
Temperament: Peaceful, shy
Color Form: Black with white spots
Lifespan: 10+ years
Size: 7–8 inches
Diet: Carnivorous
Minimum Tank Size: 50 gallons
Tank Set-Up: Saltwater, reef
Compatibility: Community marine fish, other peaceful carnivores, reef life

Marine Betta Overview

The Marine Betta is a beautiful fish with striking, dark black coloration and distinct white spots. They are peaceful fish that are native to the Indo-Pacific Ocean and are often found among reefs. These nocturnal fish become active hunters at night, searching for live prey small enough to eat.

Marine Bettas can be somewhat difficult to keep in a home aquarium due to their tendency to only eat live food they have had time to hunt. This means that if you offer them live food in a tank with more fast-acting predators, like Grouper, then the Marine Betta may not get to eat. Some people have reported their Marine Betta starving to death because of this, so care should be taken when considering tank mates and tank setup for a Marine Betta.

Marine Bettas are not true Betta fish. They are called Bettas due to their similar body shape to freshwater Betta fish and their long, elegant fins. They should not be confused with freshwater Bettas, though. They have very different needs from those of freshwater Betta fish.

How Much Do Marine Betta Cost?

Like many saltwater fish, Marine Bettas tend to come at a high price and are often found only in specialty aquarium shops and online stores. Expect to spend somewhere between $50-60 on the very low end of Marine Betta fish. Larger and higher quality fish can exceed $250. Remember that purchasing online will often result in shipping fees, which can cost you up to $35 or so.

Typical Behavior & Temperament

Marine Bettas are somewhat timid and peaceful fish that are naturally nocturnal and avoid bright lighting. During the day, they spend most of their time under overhangs and in caves resting. At night, Marine Bettas come out of their hiding place to hunt. They are active hunters that prefer to stalk live prey and rarely will eat dead prey.

marine betta close up
Image Credit: Roberto Dani, Shutterstock

Appearance & Varieties

Marine Betta fish have a deep black base coloration with white spots. Their markings are sometimes called a “starry night” pattern. They have a spot near the back end of the body that looks like an eye. In the wild, they will swim their front end into caves and crevices if they feel threatened. This leaves the back end sticking out, and the eye spot gives them the appearance of a Moray Eel sticking out of the crevice.

The white spots they have also help to camouflage them in underwater environments. This doesn’t just protect them from larger predators, but it also helps them stay hidden while stalking their prey. They have long fins and can fan their fins out to help herd prey toward their mouth and to make themselves appear larger and more threatening to predators.

How to Take Care of Marine Betta

Habitat, Tank Conditions & Setup

Aquarium Size

Marine Bettas can reach up to 8 inches in length and they are happiest in a tank with lots of space and hiding places. This means that a 50-gallon tank is the absolute bare minimum tank size for them. However, they usually are happiest in a tank that is 75 gallons or more.

Water Temperature & pH

These fish prefer warm water temperatures and usually thrive in the 72–81˚F range. They prefer an alkaline pH between 8.0–8.4 and should not be kept in acidic conditions.


The substrate you choose for your Marine Betta’s environment should be dependent on the setup of the tank. Marine Bettas do not seem to have any substrate preferences as long as they have hiding places and space to hunt.


Marine Bettas are plant-safe fish. They are carnivorous, so they will not eat plants, and they are not known to uproot plants. Depending on the setup of your tank, the plants you use may vary, but any marine plants that thrive in the same tank conditions as the Marine Betta are appropriate.


The tank should have a normal day/night lighting cycle and during the day, your Marine Betta should have plenty of places to hide away from the light. An automatic light that fades on and off is a great option for these fish. Sudden changes from dark to light can spook and stress them and may result in your fish hiding.


In saltwater tanks, sump filtration systems are often used for their efficiency and ability to protect and support delicate plants and animals. Marine Bettas do not have specific filtration needs outside of high water quality and adequate aeration.

marine betta in aquarium
Image By: Podolnaya Elena, Shutterstock

Are Marine Betta Good Tank Mates?

Marine Betta fish can make great tank mates under the right circumstances. They are peaceful fish, but they are predatory and will eat smaller fish and invertebrates. This means that tank mates should be carefully chosen. Otherwise, you may end up with your small fish and invertebrates disappearing one by one.

They can be kept in most peaceful tank environments with community fish and other carnivores. All tank mates should be peaceful since the Marine Betta can be shy and is easily stressed by aggressive tank mates. Avoid pairing them with fast-moving predators that may steal their food.

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What to Feed Your Marine Betta

Marine Bettas are fully carnivorous and prefer live foods. They can be offered feeder shrimp and small fish. Many people find that they can adjust to non-living prey once they are established in their tank environment. Once your Marine Betta is settled in and feels safe and confident, you may begin offering dead prey and work to transition them off of a live diet. This transition period may take time, though, and should be performed carefully and slowly to ensure your fish is getting enough to eat and adjusting to the new diet well.

Keeping Your Marine Betta Healthy

Marine Bettas are exceptionally hardy saltwater fish. They are highly resistant to many diseases and rarely get sick. It is important to ensure the water parameters stay in their preferred range, though. Sudden changes in parameters may lead to stress and illness. You should also work to keep your Marine Betta’s tank environment low-stress. High-stress environments can lead to a depressed immune system and an increased risk of illness.

One of the most common problems associated with Marine Bettas is malnutrition and starvation due to improper feeding or food being taken by other predators in the tank. Ensure your Marine Betta is getting plenty to eat, especially if there are other animals in the tank that may steal food offered to your Marine Betta.


It is possible to breed Marine Bettas in the home aquarium, but they do best if provided a tank specifically set up for breeding. Plenty of caves and hiding places should be provided and a high-quality diet should be provided to stimulate breeding. During spawning, the female will deposit her eggs on the wall of the chosen cave and may leave between 300-500 eggs in one breeding session.

Male Marine Bettas are extremely protective of their eggs, and as the days to hatching shorten, they will increase in aggression. In about 6 days, the eggs will hatch. The hatchlings are pretty self-sufficient and will begin hunting for small prey within a few days.

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Are Marine Betta Suitable For Your Aquarium?

Marine Betta fish can be a fantastic addition to your saltwater tank if you are prepared to give them the low-stress home they require. Marine Bettas can be happy living in a tank alone or in a community tank with peaceful tank mates. Their distinct markings and beautiful fins make them a centerpiece all their own, so you can choose your own direction with a tank for your Marine Betta fish.

If you intend to keep a Marine Betta in a community tank, ensure they are not kept with small tank mates. Otherwise, you may end up with expensive food for your Marine Betta by way of tank mates. Be prepared for the extra effort of encouraging your Marine Betta to eat and working to adjust them to non-live prey.

Featured Image Credit: JaysonPhotography, Shutterstock

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