Red Mouth Headstander, Ternetz's Anostomus

Family: Anostomidae Picture of a HeadstanderAnostomus ternetzi
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Hi - I am looking to buy headstander species, in particular Anostomus. If you have any you are willing to sell please email me: nds1971@gmail.com I am in the NYC... (more)  Nels

Headstander fish can poise in an almost vertical position, and will flip upside-down to grasp food from the substrate!

The Headstander Anostomus ternetzi is a member of the Anostomidae family. This is a fairly small family of characins, but they are all fairly large fish. This member is called a "Headstander" because it often rests almost vertically, usually at about a 45 degree incline with its head down in the rocky fissures of fast flowing waters. In the wild this fish is found in areas of streams that are shallow but with strong currents and lots of algae for these fish to eat. Common names for A. ternetzi are Headstander, Red Mouth Headstander, and Ternetz's Anostomus.

There are actually a number of other fish species from South America that are known as headstander fish. Several more headstander fish are found in the Anostomus genus. There are also headstanders from the Chilodus genus of the Chilodontidae family. This headstander fish is not quite as remarkable in color when compared to its more striking relative the Striped Headstander Anostomus anostomus, but it is also less sensitive to aquarium conditions and less territorial.

Overall this is a fairly hardy fish as long as their water is kept clean, but it is best kept by an aquarist with some fish keeping experience. This is an active fish and it attains a good size. It will reach up to about 4 3/4 inches (12 cm) in length and so will need a large aquarium of 25 gallons or more. It tends to be shy when first introduced to the aquarium and will prefer some planted areas and a darker gravel. Though generally calm, like all headstanders, it is sensitive to shadows and it likes to jump. Be sure to keep the aquarium covered.

This species is mostly a peaceful community fish, but it can be slightly aggressive. It can be kept singly, but it also does fine when kept with its own species and can be kept in pairs or small groups as well. To keep down aggression a group of 6 or more works best. This fish makes a good companion with other community tankmates that are the same size or larger.

For Information on keeping freshwater fish, see:
Freshwater Aquarium Guide: Aquarium Setup and Care

Geographic Distribution
Anostomus ternetzi
Data provided by FishBase.org
  • Kingdom: Animalia
  • Phylum: Chordata
  • Class: Actinopterygii
  • Order: Characiformes
  • Family: Anostomidae
  • Genus: Anostomus
  • Species: ternetzi
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Headstander - Quick Aquarium Care
  • Aquarist Experience Level: Intermediate
  • Size of fish - inches: 4.7 inches (11.99 cm)
  • Minimum Tank Size: 25 gal (95 L)
  • Temperament: Peaceful
  • Aquarium Hardiness: Moderately hardy
  • Temperature: 75.0 to 82.0° F (23.9 to 27.8° C)
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Habitat: Distribution / Background

The Headstander Anostomus ternetzi was described by Fernández-Yépez in 1949. This species is not listed on the IUCN Red List. Its common names included Headstander as well as Red Mouth Headstander and Ternetz's Anostomus. They are found in South America in Brazil in the Amazon River basins of Orinoco, Rio Araguaia, and Rio Xingo; and in the coastal rivers of Guianas.

The headstander inhabits the fast-flowing parts of rivers where the water is shallow but with strong currents, and that has lots of algae for these fish to eat. They will spawn on the vegetation and on the bottoms of these streams. These are omnivores that feed on aquatic plants, algae, small invertebrates, and insects.

  • Scientific Name: Anostomus ternetzi
  • Social Grouping: Groups - In general Anostomus are a peaceful, schooling species.
  • IUCN Red List: NE - Not Evaluated or not listed


The Headstander is an elongated fish with a pike type body. This fish will reach almost 4 3/4 inches (12 cm) in length and has a life span of 5 - 8 years. It has a dark brown to black body with two broad white to reddish stripes running the entire length of the body from the snout to the caudal peduncle. Its fins are transparent, sometimes with a light brown cast.

  • Size of fish - inches: 4.7 inches (11.99 cm)
  • Lifespan: 8 years - They have a lifespan of 5 - 8 years in the aquarium.

Fish Keeping Difficulty

The Headstander is a fairly hardy fish and well suited for an aquarist with some fish keeping experience. Water quality should always be maintained. For the best results with these fish make sure to offer algae for them to feed on.

  • Aquarium Hardiness: Moderately hardy
  • Aquarist Experience Level: Intermediate

Foods and Feeding

In the wild this Headstander will feed on algae, aquatic plants, insects, and small invertebrates. Since they are omnivorous, in the aquarium these fish will generally eat all kinds of live, fresh, and flake foods. To keep a good balance give them a high quality flake food everyday along with a good spirulina formula fish food or algae wafer. Feed brine shrimp (either live or frozen) or blood worms as a treat.

They will also enjoy other vegetable matter such as chickweed, watercress, crushed lettuce leaves and spinach leaves. They may nibble on the aquarium plants soft shoots and leaves, especially if there is not enough algae growth in the tank. They do best when fed several times a day. Offer only what they can eat in 3 minutes or less at each feeding.

  • Diet Type: Omnivore
  • Flake Food: Yes
  • Tablet / Pellet: Yes
  • Live foods (fishes, shrimps, worms): Some of Diet
  • Vegetable Food: Some of Diet
  • Meaty Food: Some of Diet
  • Feeding Frequency: Several feedings per day

Aquarium Care

The Headstanders are not exceptionally difficult to care for provided their water is kept clean. Aquariums are closed systems and regardless on size all need some maintenance. Over time decomposing organic matter, nitrates, and phosphate build up and the water hardness increases due to evaporation. To combat these ever changing conditions water should be replaced on a regular basis, especially if the tank is densely stocked. At least 25 - 50% of the tank water should be replaced every other week.

  • Water Changes: Bi-weekly

Aquarium Setup

These fish are somewhat less demanding than their cousin the Striped Headstander Anostomus anostomus and can be kept singly, in pairs, or in small groups. The do get pretty big and will need at least a 25 gallon aquarium or larger. They like some planted areas, layered rocks, and a darker gravel. Some species may nibble on soft plants. Make sure the tank has a tight fitting cover as these fish are great jumpers.

The Headstander does well in a biotype tank setup. For this type of setup the substrate should be a soft river sand with piles of rocks and driftwood throughout the tank. There needs to be a lot of surfaces that will encourage the growth of algae. A bright light will also help to encourage algae growth, which will be a great supplemental food. A River Manifold system can be installed to give this fish a good current. But a canister filter and powerheads can be used in place of the manifold system if preferred. Keep in mind that if you add plants to the tank these fish may eat them, especially the new soft shoots and leaves.

  • Minimum Tank Size: 25 gal (95 L)
  • Suitable for Nano Tank: Yes - They can be kept in one of the largest nano tanks.
  • Substrate Type: Small Gravel - This fish appreciates a darker colored small gravel or sand.
  • Lighting Needs: Low - subdued lighting
  • Temperature: 75.0 to 82.0° F (23.9 to 27.8° C)
  • Breeding Temperature: 80.0° F - Suggested breeding parameters are temperatures between 77 - 82° F (25 - 27° C), pH between 6 - 7, and a hardness of 10° KH.
  • Range ph: 5.8-7.5
  • Hardness Range: 5 - 20 dGH
  • Brackish: No
  • Water Movement: Moderate
  • Water Region: All

Social Behaviors

The Headstander is peaceful overall, but can be slightly aggressive at times. They can be kept singly but they also get along fine with their own kind. They can be kept as a pair or in a group. In a small group however they will become aggressive, so to cut down on aggression keep at least 6 or more of their own kind.

They are good for a community aquarium with other peaceful fish that are the same size or larger. But avoid fish that demand the same foods. For example the Headstander may not fare well in competition with catfish from the genus Hemiancistrus, the Chinese Algae Eaters of the Gyrinocheilus genus, or freshwater sharks from the genus Epalzeorhynchos.

  • Venomous: No
  • Temperament: Peaceful
  • Compatible with:
    • Same species - conspecifics: Yes - They can be kept in pairs or in groups of 6 or more of their own kind.
    • Peaceful fish (): Safe - A good community fish with tankmates of the same or larger size.
    • Semi-Aggressive (): Threat
    • Semi-Aggressive (): Threat
    • Aggressive (): Threat
    • Large Semi-Aggressive (): Threat
    • Large Aggressive, Predatory (): Threat
    • Slow Swimmers & Eaters (): Monitor
    • Shrimps, Crabs, Snails: Safe - not aggressive
    • Plants: Monitor - Some headstander species will eat soft plants.

Sex: Sexual differences


Breeding / Reproduction

In nature the Headstanders are a spawning fish that shed their eggs after a pairing at the surface. Breeding Anostomus has been accomplished in captivity but no firm data is available. It is very rare and there is as of yet no developed method proven effective.

For a chance to be successful at breeding them in captivity, it is suggested to separate the males from the females. Condition them by feeding them live foods. Provide a large spawning tank that is at least 3 1/3 feet (1 m) long with a sandy bottom, a few roots and stones with algae, and some peat filtration to add a touch of acid. Suggested water parameters are a pH between 6 - 7, a hardness of 10° KH, and with a temperature that matches their regular tank.

Introduce the males and females into the prepared tank and increase the temperature to between 77 - 82° F (25 - 27° C). Cover the top with a towel, creating a darkened environment to help trigger the spawn. Pairing should occur quickly just below the surface of the water, with 3 - 5 eggs 1.5 mm in size being shed. Take the parents from the tank once the eggs are shed as they have a tendency to eat them. Feed the newly hatch fry brine shrimp nauplii, Cyclops, and algae.

Although breeding Anostomus is unknown the method above is a compilation of suggestions, including information from authors Dr. Rudiger Riehl and Hans A. Baensch in their book, Aquarium Atlas Vol. 1 (1991). In the breeding section of the species Anostomus anostomus, they point to breeding of the closely related Spotted Headstander Chilodus punctatus. The spawning tank decor and parameters above are derived from the breeding of C. punctatus in an account by Geisler, originally published in the West German Magazine DATZ. Also see a description of breeding characin fish here: Breeding Freshwater Fish: Characins.

  • Ease of Breeding: Difficult

Fish Diseases

The Headstanders are hardy and disease is not usually a problem in a well maintained aquarium. That being said there is no guarantee that you won't have to deal with health problems or disease. Anything you add to your tank can bring disease to your tank. Not only other fish but plants, substrate, and decorations can harbor bacteria. Take great care and make sure to properly clean or quarantine anything that you add to an established tank so not to upset the balance.

A good thing about the Headstanders is that due to their resilience, an outbreak of disease can often be limited to just one or a few fishes if you deal with it at an early stage. When keeping more sensitive types of fish, it is common for all fishes to be infected even before the first warning signs can be noticed. The best way to proactively prevent disease is to give your Flame Tetra the proper environment and give them a well balanced diet. The closer to their natural habitat the less stress the fish will have, making them healthier and happy. Stressed fish are more likely to acquire disease.

As with most fish they are prone to skin flukes, parasitic infestations (protozoa, worms, etc.), ichthyobodo infection, parasitic infestations (protozoa, worms, etc.), bacterial infections (general), and bacterial disease. It is recommended to read up on the common tank diseases. Knowing the signs and catching and treating them early makes a huge difference. For information about freshwater fish diseases and illnesses, see Aquarium Fish Diseases and Treatments.


The Headstander is occasionally available from time to time in pet stores and online, and is moderately priced.


Author: David Brough CFS, Jeremy Roche
Lastest Animal Stories on Headstander

Nels - 2015-10-18
Hi - I am looking to buy headstander species, in particular Anostomus. If you have any you are willing to sell please email me: nds1971@gmail.com I am in the NYC area.

mark - 2009-01-14
Mine has a red tail is this the same fish??
Also ive heard that these fish can eat the scales of other fish is this true

joe - 2008-03-26
My fish is 10 and with help of this website I hope it can live to be 20.

Anonymous - 2008-02-25
My headstander lived to be 22 years old, I had no idea they would live that long!

Nels - 2015-10-18
Hi - I am looking to buy headstander species, in particular Anostomus. If you have any you are willing to sell please email me: nds1971@gmail.com I am in the NYC area.