Glass Tetra (Moenkhausia oligolepis): Overview and Care Guide

glass tetra care
Japanese Fighting Fish is reader-supported. When you purchase through one of our links we may earn an affiliate commission (at no extra cost to you).

Last Updated: July 8, 2023 by Flora Gibbins

Imagine a fish so mesmerizingly transparent that it appears almost invisible, as if made from delicate shards of glass. Meet the Glass Tetra (Moenkhausia oligolepis), a unique and fascinating species that has enthralled aquarists for decades. Known for their captivating appearance and peaceful demeanor, these fish are a popular choice for community aquariums.

This blog post will explore various aspects of the Glass Tetra, from its origin and distribution to its care requirements, tank setup, and breeding.

Glass Tetra Facts and Overview

  • Common names: Glass Tetra, Clear Tetra
  • Scientific name: Moenkhausia oligolepis
  • Adult size: 2 inches (5 cm) in length
  • Lifespan: 3 to 5 years
  • Colors and Markings: Transparent body with silver and green iridescence; occasional black markings on the dorsal fin
  • Origin: South America, specifically the Amazon Basin and surrounding areas


The Glass Tetra (Moenkhausia oligolepis) is truly a sight to behold, thanks to its unique and captivating appearance. The most eye-catching thing about these fish is their nearly see-through bodies, which is actually where they get their name. It’s pretty cool how this transparent feature helps them blend right in with their natural environment.

Growing up to 2 inches (5 cm) in length, Glass Tetras display a slender, elongated body shape that is characteristic of many tetra species. The transparency of their bodies is complemented by a shimmery sheen that can appear silver or green, depending on the lighting and angle of view. This shimmering effect adds an ethereal beauty to their appearance, further enhancing their appeal in the home aquarium.

One of the few opaque features of the Glass Tetra is its dorsal fin, which may exhibit black markings or bands, creating a subtle contrast against the otherwise see-through body. The combination of transparency, iridescence, and occasional dorsal markings make the Glass Tetra a truly unique and mesmerizing addition to any community aquarium.

glass tetra school

Behavior and Temperament

Glass Tetras are peaceful and social fish, which makes them great for community aquariums. They are schooling fish, which means they feel most secure and comfortable when in the company of their own kind. So do keep Glass Tetras in a group of at least six to ensure they are happy and well so you can observe their most natural and engaging behavior.

In a well-established group, Glass Tetras will often swim together in a coordinated way, displaying fascinating schooling behavior that is both beautiful and captivating to watch. They are generally active swimmers and are known to occupy the middle and upper areas of the water column in the aquarium.

Despite their delicate appearance, Glass Tetras are quite hardy and can adapt well to a variety of environments, provided that their basic care requirements are met. They are non-aggressive and will peacefully coexist with other similarly sized and temperament fish species.

It is essential to provide Glass Tetras with a suitable environment that includes hiding spots, such as live plants, rocks, or driftwood, where they can retreat if they feel threatened or stressed. In a well-planned and maintained aquarium, these fascinating fish will display their most intriguing and endearing behaviors, making them a true delight to observe.

Glass Tetra Tank Mates

Compatible Fish Species

Glass Tetras, with their peaceful temperament, can coexist harmoniously with a variety of tank mates. Ideal companions include other similarly sized and non-aggressive fish species. Some suitable tank mates are:

  • Other Tetra species (e.g., Neon Tetras, Lemon Tetras, Glowlight Tetras, Diamond Tetras)
  • Rasboras
  • Corydoras Catfish
  • Small species of Gouramis (e.g., Honey Gourami, Dwarf Gourami)
  • Livebearers (e.g., Guppies, Mollies, Platies)
  • Hatchetfish
  • Dwarf Cichlids (e.g., Apistogramma, Kribensis)

Non-Fish Tank Mates

In addition to compatible fish species, Glass Tetras can also share their aquarium with certain peaceful invertebrates. Some suitable non-fish tank mates include:

  • Cherry Shrimp
  • Ghost Shrimp
  • Amano Shrimp
  • Nerite Snails
  • Mystery Snails

Tank Mates to Avoid

To ensure the safety and well-being of Glass Tetras, it’s essential to avoid housing them with larger, aggressive, or predatory fish species that might see them as food or cause them undue stress. Some tank mates to avoid include:

  • Larger Cichlids (e.g., Oscars, Jack Dempsey, Green Terrors)
  • Aggressive species (e.g., Tiger Barbs, Red-tailed Black Shark)
  • Predatory fish (e.g., Arowanas, Bichirs, Pictus Catfish)

Glass Tetra Care: The Art of Fostering a Thriving Underwater World

Embarking on the journey of Glass Tetra care means embracing the fascinating challenge of creating a thriving underwater habitat for these ethereal beings. As the guardians of these delicate aquatic gems, it’s our responsibility to ensure their well-being and happiness by providing them with the essential elements of a healthy and balanced environment.

Let’s go into more detail about the most important aspects of caring for Glass Tetras.

Tank Setup

Tank Size

Glass Tetras are active swimmers that appreciate having ample space to explore and school with their companions. A minimum tank size of 20 gallons is recommended for a small group of Glass Tetras, but larger tanks are always encouraged as they provide more room for swimming and better water quality.

What to Put In Their Tank

To replicate their natural habitat and provide a sense of security, it’s essential to include:

  • Live plants: Plants like Java Fern, Anubias, Amazon Sword, and Cryptocoryne can provide shelter and hiding spots, as well as enhance water quality. Floating plants like Duckweed or Water Lettuce can help diffuse lighting and create a more natural environment.
  • Driftwood: Adding pieces of driftwood can create an attractive and naturalistic environment, providing additional hiding spots and mimicking their natural habitat.
  • Rocks and caves: Incorporating rocks and caves will provide additional shelter and resting spots for your Glass Tetras, ensuring they feel secure and comfortable.


A high-quality filter is essential for maintaining optimal water quality in your Glass Tetra tank. Choose a filter that is rated for the size of your aquarium and offers mechanical, chemical, and biological filtration. Additionally, consider a filter that generates a gentle water flow, as Glass Tetras prefer calm water conditions.


Glass Tetras are not overly particular about the substrate in their environment. However, to create a visually appealing and natural-looking tank, you can use dark-colored sand or fine gravel. A darker substrate can also help accentuate the iridescent colors of Glass Tetras, making them stand out more in the aquarium.

Water Parameters

Maintaining appropriate water parameters is crucial for the health and well-being of your Glass Tetras. By closely replicating their natural habitat conditions, you can ensure that your fish thrive and exhibit their best colors and behavior. Here are the key water parameters for this species:

  • Temperature: Glass Tetras prefer a water temperature between 72°F and 78°F (22°C to 26°C). Use an aquarium heater and a reliable thermometer to maintain a stable temperature within this range.
  • pH: The ideal pH range for Glass Tetras is between 6.0 and 7.5. To maintain stable pH levels, perform regular water tests and avoid making abrupt changes to the water chemistry.
  • Hardness: Glass Tetras can adapt to a range of water hardness levels. However, they generally prefer soft to moderately hard water, with a hardness level between 5 and 15 dGH.
  • Water Quality: Maintain good water quality by performing regular water changes, typically 25% to 30% every two weeks. This will help remove waste and toxins, and keep the water clear and clean. Use a water conditioner to remove unwanted elements such as chlorine and chloramines when adding new water to the tank.
  • Ammonia, Nitrite, and Nitrate: Monitor ammonia, nitrite, and nitrate levels regularly using a water testing kit. Ammonia and nitrite levels should always be at 0 ppm, while nitrate levels should be kept below 20 ppm. Maintaining a well-functioning filtration system and performing regular water changes can help keep these levels in check.

Diet and Feeding

Glass Tetras are pretty laid-back when it comes to food, being omnivores who enjoy munching on both plants and small critters. To ensure they stay healthy, energetic, and show off their lovely colors, just remember to give them a well-balanced diet.

Let me walk you through some great food choices for your Glass Tetras:

  • High-quality flake or pellet food: Choose a high-quality, nutritionally balanced flake or pellet food specifically formulated for tropical fish as the staple of their diet. This will ensure they receive the essential vitamins, minerals, and nutrients needed for optimal health.
  • Live and frozen foods: Supplement their diet with a variety of live or frozen foods, such as brine shrimp, daphnia, bloodworms, and tubifex worms. These protein-rich foods can help enhance their colors and support overall well-being.
  • Vegetable matter: Don’t forget to add a little veggie action to their meals, like some blanched spinach or zucchini. It’ll give them extra nutrients and make their diet more interesting.

Feed your Glass Tetras in small portions, ideally two to three times a day. Offer them only the amount of food they can consume within 2-3 minutes to avoid overfeeding and maintain good water quality.

glass tetra
Credit: Fernando Dagosta

Common Diseases and Health Issues

Just like any other fish species, Glass Tetras can be susceptible to certain diseases and health issues if they are not well taken care of. A lot of these issues are preventable just by maintaining optimal water conditions and feeding the fish a balanced diet.

Here are some common health problems and diseases that you should look out for:

  • Ich (White Spot Disease): Ich is a common parasitic infection in aquarium fish, characterized by small white spots on the fish’s body, fins, and gills. If you notice these symptoms, promptly raise the water temperature to 86°F (30°C) for a few days and treat the tank with an appropriate medication.
  • Fin Rot: This bacterial infection affects the fish’s fins, causing them to appear frayed or discolored. To treat Fin Rot, improve water quality through regular water changes, and consider using a medication specifically designed for this condition.
  • Swim Bladder Disease: This disorder can cause your Glass Tetras to have difficulty swimming, appearing unbalanced or floating at odd angles. It can often be linked to overfeeding or a lack of dietary fiber. Adjust their diet accordingly and, if necessary, consider using a medication that targets swim bladder issues.
  • Parasites and Fungal Infections: Glass Tetras can occasionally suffer from external parasites, such as anchor worms or gill flukes, or fungal infections. If you notice any unusual growths, spots, or changes in behavior, consult a specialist and use the appropriate medication to treat the issue.

Here are some preventive measures you can apply:

  • Quarantine new fish: Before introducing new fish to your aquarium, keep them in a separate quarantine tank for two weeks to observe them for any signs of illness.
  • Regular water changes: Perform routine water changes and maintain optimal water parameters to ensure a healthy environment for your Glass Tetras.
  • Balanced diet: Provide a varied, well-balanced diet to support your Glass Tetras’ immune system, helping them fight off diseases and infections.
  • Avoid stress: Minimize stress by providing a comfortable environment with ample hiding spots, maintaining a consistent water temperature, and avoiding sudden changes in water chemistry.

Breeding Glass Tetras

Breeding Glass Tetras can be a rewarding and fascinating experience for any aquarist. By understanding and following the various steps involved in the breeding process, you can increase your chances of success and witness the captivating dance of reproduction.

Here’s a step-by-step guide to help you achieve successful spawning:

  1. Sexing your fish: Before anything else, you have to identify your male and female Glass Tetras. Males are generally slimmer and more streamlined, while females have a rounder, fuller body, particularly when carrying eggs. Additionally, males may exhibit slightly more vibrant coloration.
  2. Setting up a breeding tank: To encourage breeding, set up a separate, dimly lit tank with soft, slightly acidic water (pH 6.0-6.5) and a temperature between 75°F and 80°F (24°C-27°C). Include fine-leaved plants or a spawning mop for the fish to lay their eggs on.
  3. Conditioning the breeding pair: Feed the potential breeding pair a high-quality diet rich in live and frozen foods for 1-2 weeks to encourage the development of eggs in the female and prepare them for spawning.
  4. Introducing the breeding pair: Place the conditioned male and female Glass Tetras into the breeding tank, preferably in the evening, as they often spawn during the early morning hours.
  5. Spawning: When the fish are ready to spawn, they will engage in a courtship dance, culminating in the female releasing her eggs, which the male will fertilize. Glass Tetras may lay up to 200 eggs during spawning.

Here are some additional breeding tips:

  • Post-spawning care: Once spawning has occurred, remove the adult fish from the breeding tank to prevent them from eating the eggs. Glass Tetra eggs are adhesive and will stick to the plants or spawning mop.
  • Egg incubation: Maintain optimal water parameters in the breeding tank, and keep the lighting dim, as Glass Tetra eggs are sensitive to light. The eggs will typically hatch within 24-36 hours.
  • Feeding the fry: Once the fry become free-swimming (usually within 3-5 days after hatching), start feeding them a diet of infusoria or commercially available fry food. Gradually introduce them to baby brine shrimp and finely crushed flake food as they grow.

Related Species

Glass Tetras belong to a large family of fish called Characidae, which includes numerous other species of Tetras. If you’re interested in learning more about similar fish, here’s a list of related species that you might consider for your aquarium:

  • Lemon Tetra (Hyphessobrycon pulchripinnis): Known for their subtle yellow coloration and peaceful demeanor, Lemon Tetras make great companions for Glass Tetras.
  • Glowlight Tetra (Hemigrammus erythrozonus): Characterized by their orange-red iridescent stripe, Glowlight Tetras are another lesser-known species that can peacefully coexist with Glass Tetras.
  • Black Neon Tetra (Hyphessobrycon herbertaxelrodi): Despite their name, Black Neon Tetras are not as well-known as Neon Tetras but are a peaceful species that can be a good match for Glass Tetras.
  • Flame Tetra (Hyphessobrycon flammeus): Also known as Red Tetra or Rio Tetra, the Flame Tetra displays striking red coloration and a peaceful nature, making them an excellent choice for a community tank with Glass Tetras.
  • Diamond Tetra (Moenkhausia pittieri): With their shimmering silver scales, Diamond Tetras are another lesser-known species that can be compatible with Glass Tetras in a community aquarium.

FAQs on Glass Tetras

Can Glass Tetras change color?

Yes, Glass Tetras can change color in response to various factors, such as stress, water conditions, diet, or lighting. Providing a comfortable environment, proper nutrition, and suitable water parameters will help maintain their vibrant coloration.

How fast do Glass Tetras grow?

Glass Tetras typically reach their adult size of around 2 inches (5 cm) within 6-8 months, depending on the quality of care, diet, and water parameters provided.

Can I keep Glass Tetras in a nano tank?

While Glass Tetras are small, they are active swimmers and prefer to be in groups. A nano tank might not provide enough swimming space for a school of Glass Tetras. It’s recommended to keep them in tanks of at least 20 gallons (76 liters) or larger.

How many Glass Tetras can I keep in a 20-gallon (76-liter) tank?

In a 20-gallon (76-liter) tank, you can comfortably keep a school of 6-8 Glass Tetras, considering the 1-inch-per-gallon rule. However, this number may vary depending on the presence of other tank inhabitants and the tank’s layout.

Do Glass Tetras jump?

Like many other tetra species, Glass Tetras may jump when startled or stressed. It’s a good idea to have a well-fitting lid on your aquarium to prevent escape or injury.

Are Glass Tetras Right for Your Aquarium?

Embark on this rewarding journey with enthusiasm, persistence, and a commitment to learning. As you explore the diverse world of Tetra fish, you’ll be rewarded with the satisfaction of creating a vibrant, harmonious underwater haven that reflects the beauty and complexity of their natural habitats.

Leave a Comment

Your email address will not be published. Required fields are marked *