Gem Tang: Your Friendly Guide to This Precious Stone

The Gem Tang (Zebrasoma gemmatum) is a highly sought-after saltwater fish known for its magnificent appearance and captivating charm. As an aquarium enthusiast, you might be curious to learn more about this stunning species and how to provide the best care possible.

This spectacular fish sports a blue-black body adorned with brilliant white spots and a vibrant yellow tail, making it a visually striking addition to any marine aquarium. With a potential lifespan of 30 years, the Gem Tang can become a long-term aquatic companion for those who are up for the challenge.

In the upcoming sections, we will explore the ideal tank environment, nutrition, and maintenance strategies to keep your Gem Tang thriving. As you continue along this journey, you’ll gain invaluable insights into creating the perfect underwater haven for this beautiful and rare species.

Species Overview

The Gem Tang is a striking saltwater fish that boasts vibrant colors and unique patterns, making it a popular choice for many aquarium enthusiasts. Below, you’ll find key information about this beautiful species to help guide your fishkeeping journey.

Property Details
Scientific name Zebrasoma gemmatum
Common names Gem Tang, Gemmatum Tang, Spotted Tang, Mauritius Tang
Distribution Western Indian Ocean
Size Up to 8.7 inches (22 cm)
Lifespan Not specified
Diet Herbivore
Temperament Moderate
Minimum tank size 180 gallons (681 L)
Temperature Not specified
pH Not specified
Water hardness Not specified
Care level Moderate
Filtration/Water Flow Not specified
Water type Saltwater
Breeding Not specified
Breeding difficulty Not specified
Compatibility Reef safe

To provide the best care for your Gem Tang, make sure its tank is well-maintained and meets the required water conditions. In terms of diet, ensure your Gem Tang has plenty of herbivorous food to thrive. And lastly, when considering tank mates, be mindful of your fish’s temperament and compatibility to create a harmonious aquatic environment.

Gem Tang Basics

Origins And Natural Habitat

Gem Tangs are beautiful saltwater fish that originate from the western Indian Ocean. They are a rare species, admired by many fish enthusiasts due to their unique appearance. In the wild, they typically inhabit shallow coral reefs, making them an ideal choice for reef-based aquarium setups.

Size And Shape

When it comes to size, adult Gem Tangs can reach up to 8.7 inches (22 centimeters) in length. On the other hand, juveniles are usually around 2-3 inches long. Their body shape is disc-like, which is common among the Tang fish family. This flattened shape allows them to swim effortlessly and navigate through narrow crevices in the coral reefs.

Color And Markings

The Gem Tang is known for its striking appearance, combining vibrant colors and fascinating markings. They have a dark blue body that’s adorned with a pattern of brilliant white spots. The yellow anal fin adds a bright, contrasting touch to their overall appearance, making them truly stand out in any aquarium setting.


In the wild, Gem Tangs can live up to an impressive 25 years. However, when kept in captivity, their lifespan can range between 7 and 10 years. Providing them with proper care, including a nutrient-rich diet and stable living conditions, can result in a longer life expectancy. Just remember that these fish require a good deal of attention and adequate tank space to grow and thrive.

Diet And Feeding

Feeding your Gem Tang a balanced diet is essential for its health and well-being. As herbivores, they primarily graze on algae and enjoy a variety of vegetables.

You can provide your Gem Tang with live rocks to graze on. This is not only a natural food source but also helps keep them entertained. If you have other herbivores in the tank, provide additional food to prevent competition.

Here are some suggestions for your Gem Tang’s diet:

  • Nori: This seaweed is a popular choice and can be easily found in stores.
  • Broccoli and zucchini: Chop these vegetables finely and offer them occasionally to add variety.
  • Specialized pellets: Opt for pellets specifically designed for herbivorous fish.

Make sure to feed your Gem Tang a mix of these food options to ensure their nutritional needs are met. Keep an eye on their appetite and adjust the feeding quantity as necessary. A healthy, well-fed Gem Tang will be more active, colorful, and less prone to diseases.

Behavior And Temperament

Gem Tangs, scientifically known as Zebrasoma gemmatum, are beautiful saltwater fish with unique personalities. They tend to be semi-aggressive and may fight with other tangs, especially those from the same Zebrasoma species.

To keep your fish stress-free and healthy, provide them with enough space and hiding spots in their tank environment. A minimum tank size of 180-gallons (681L) is recommended.

When selecting tank mates for your Gem Tang, consider peaceful and compatible species. Avoid housing them with other tangs or any fish that might compete with them for territory or food.

As herbivores, it is crucial to maintain a nutritious diet of algae, seaweed, and vegetable matter. A balanced diet will help reduce stress and promote better behavior in your Gem Tang.

Remember, observing and understanding their behavior and temperament is essential for maintaining a thriving aquarium for your Gem Tang and its tank mates.

Care And Tank Requirements

Tank Size

When planning for your Gem Tang, it’s essential to provide ample swimming space for this active fish. You should start with a minimum tank size of 180 gallons (681L) to give them plenty of room to roam and explore, as they love to do.

Water Parameters

Keep your Gem Tang happy and healthy by maintaining the appropriate water conditions in your tank:

  • pH: 8.1 – 8.4
  • Temperature: 74°F – 82°F (24°C – 28°C)
  • Specific Gravity (SG): 1.021 – 1.025
  • Carbonate Hardness (dKH): 8 – 12°

Use a water testing kit regularly to ensure your tank stays within these parameters, and make adjustments as needed.

Tank Setup And Decorations

To create a comfortable environment for your Gem Tang, you’ll need the following items:

  • Lots of hiding spaces, such as rocks, fish caves, or even faux corals
  • A spacious area for the Gem Tang to swim and explore
  • Reef-safe decorations, since Gem Tangs are reef-compatible

Remember to create adequate hiding places for your fish, as they enjoy retreating to these spaces, but keep the overall tank layout happy and friendly.

Filtration And Aeration

Proper filtration and aeration are crucial factors to keep your Gem Tang’s home clean and healthy. Ensure you have a robust filtration system in place to eliminate waste and maintain water quality.

Aeration is also essential, as it helps create water movement and oxygenation, promoting a healthy tank environment. Consider using air stones, water pumps, or powerheads to keep the water circulating and maintain a well-oxygenated environment.

By following these care and tank requirements, you’ll create an ideal home for your Gem Tang, allowing them to thrive in a comfortable, healthy environment.

Suitable Tank Mates

Gem Tangs are generally peaceful fish but may have issues with others of their own kind. Hence, it’s essential to choose compatible tank mates that will coexist well with your Gem Tang, minimizing any potential conflicts and promoting a harmonious tank environment. Here’s a list of suitable tankmates for your Gem Tang:

  • Lawnmower blennies
  • Midas blennies
  • Tailspot blennies
  • Firefish gobies
  • Neon gobies
  • Yellow watchman gobies
  • Yellow coris wrasses
  • Snowflake clownfish
  • Pink skunk clownfish

When setting up your aquarium, make sure to include fish from this list in order to ensure a peaceful environment for your Gem Tang. Proper selection of tankmates is crucial in maintaining their well-being and encouraging their peaceful behavior. Remember, a friendly and harmonious tank is vital for your Gem Tang to thrive and showcase its vibrant colors.


Breeding Gem Tangs in captivity is a challenging task for you. One issue you will face with these fish is the difficulty in gender identification, making it harder for you to pair them properly. Additionally, Gem Tangs have a spike on their back, which can make handling them quite tricky.

Another challenge you’ll encounter when attempting to breed is that Gem Tangs practice broadcast spawning. In this process, the male and female release their eggs into the water, making it difficult for you to monitor and control the breeding process. This also increases the complexity of raising the fry.

It’s also important to note the rarity and beauty of Gem Tangs, which contribute to their high cost. This is because successful captive breeding has not been widely achieved, and as a result, most of the Gem Tangs available for purchase are wild-caught. Although breeding these fish is not impossible, it’s important to be aware of the low success rate of captive breeding.

In summary, if you decide to venture into breeding Gem Tangs, be prepared for the challenges and obstacles that come with it. Keep a friendly and patient approach as you work on mastering the art of breeding these mesmerizing fish.

Common Diseases And Treatments

As a Gem Tang owner, it’s important for you to be aware of the common diseases affecting these beautiful marine fish and how to treat them.

Ich (Cryptocaryon irritans): You might notice small white dots on your Gem Tang’s body. Prevent Ich by quarantining new arrivals and maintaining good water quality.

Marine Velvet (Amyloodinium ocellatum): If you see a fine gold or brown dust on your fish’s body, it may be Marine Velvet. Prevent this disease by quarantining new fish, maintaining water quality, and using a UV sterilizer.

Lateral Line Erosion (HLLE): Pitting and erosion along the lateral line and head are signs of HLLE. Ensure a varied diet and optimal water quality to prevent this issue.

Bacterial infections: Open sores and discolored patches could indicate a bacterial infection. To prevent them, maintain good water quality and reduce stress in your aquarium.

Internal parasites: Watch for weight loss and abnormal feces, which can indicate internal parasites. Quarantine new fish and provide parasite-free food to help prevent this issue.

Prioritizing prevention is crucial to maintain the health of your Gem Tangs. Focus on a clean and stable environment, proper nutrition, and quarantine procedures. Regular water changes, testing water parameters, and monitoring fish behavior can help detect issues early for timely treatment and prevention. By following these prevention methods, you can reduce the risk of diseases and promote the overall health of your Gem Tangs in your aquarium.

Frequently Asked Questions

Are Gem Tangs reef safe?

Yes, Gem Tangs are considered reef safe. They can be a great addition to your reef aquarium, as they typically do not harm corals or other invertebrates. However, always monitor their behavior to ensure compatibility with your specific reef setup.

How aggressive are Gem Tang fish?

Gem Tangs are generally peaceful and can coexist with other marine fish in a community tank. However, they may show some territorial behavior, particularly towards other Tangs or similar looking fish. It’s best to introduce them into a well-established tank with plenty of hiding places and room to swim.

What is the ideal tank size for Gem Tang?

A minimum tank size of 180 gallons (681L) is recommended for Gem Tangs. This allows them enough space to swim, explore, and graze, as they are quite active. Having a larger tank also helps in reducing territorial behavior and ensures a healthier environment for your fish.

How do you identify a healthy Gem Tang?

A healthy Gem Tang should have a bright and vibrant coloration, smooth skin without any spots or damage, and clear eyes. Their bodies should be well-rounded and not showing any signs of malnutrition or diseases. They should also display active swimming behavior and show a healthy appetite when feeding.

What types of food do Gem Tangs prefer?

Gem Tangs are herbivores, and their diet mainly consists of algae and other plant-based foods. Provide them with marine algae, spirulina, or seaweed sheets to satisfy their grazing needs. Additionally, you can supplement their diet with a variety of vegetables such as blanched romaine lettuce, spinach, or zucchini. Ensure a well-balanced diet to help maintain their overall health.