Amazon Puffer
Colomesus asellus
The *Colomesus asellus* (Amazon Puffer) is the friendly "anomaly" of the pufferfish family: it is one of the very rare puffers to be a true schooling fish, constantly in motion, and totally peaceful towards other species, making it an excellent guest for South American community aquariums. Unfortunately, its greatest quality clashes with its greatest flaw: the fused teeth grow at such an exorbitant rate that, even with a diet based on hard snails, the aquarist will periodically have to sedate the fish and manually file its teeth.
Water Temperature
22 - 28 °C
pH Value
5.5 - 7.5
Water type
Freshwater
Tank level
Bottom and middle
Adult size
8 cm
Minimum tank volume
>= 150 L
Minimum group
>= 3
GH
2 - 12 dGH
KH
1 - 6 dKH
TDS
40 - 240 ppm
Conductivity
63 - 375 uS/cm
Species description
Geographical Origin and Habitat: Extensive throughout the Amazon River basin (Brazil, Colombia, Peru). Frequents the banks of large rivers rich in roots and flooded meadows. Never migrates to brackish water.
Taxonomy and Morphology: Amazon Puffer (Colomesus asellus). The only pure freshwater puffer fish from South America regularly imported. Reaches 8 cm (3.1 inches). Stocky "puppy" face and plaque teeth that grow at an impressive rate.
Social Behavior: Unlike most puffer fish (often solitary assassins), the Amazon Puffer is extremely sociable. Tends to move in small nervous schools, incessantly swimming up and down the glass looking for food.
Coloration and Sexual Dimorphism: Immaculate white belly, bright yellowish-green back crossed by 5-6 unmistakable black bands that cross it like a "saddle". Sexual dimorphism invisible to the naked eye.
Care, breeding and tankmates
Aquarium Setup: At least 100 cm (40 inches) in length: they swim hyperactively. It is crucial to break the visual lines with large roots, otherwise they will develop stereotypies (up and down against the glass forever). No need for marine salt.
Diet and Feeding: THE GREAT CHALLENGE: the teeth grow so fast that if not filed they will close the mouth starving it to death. Demands huge daily quantities of live snails (Physa, Ramshorn), clams with shell or frozen bloodworms mixed with crushed shells.
Water Quality: Completely freshwater, intolerant of salt. Extremely sensitive to ammonia and nitrates, the water must be over-filtered (the remains of snail shells pollute a lot).
Compatibility and Cohabitation: Paradoxically peaceful, but it is still a "fin-nipper". Often mutilates slow fish or those with veil fins (Corydoras, Angelfish). Should be kept in groups of 6+ with fast Loricariids or darting Characins.
Aquarium Breeding: Never documented. It is only known that in nature they gather in thousands laying small pelagic eggs that scatter in the current of the great Amazonian rivers.
Risks and Diseases: 90% of improperly cared for specimens require manual dental intervention: the aquarist must sedate the fish (with clove oil) and cut its teeth with cuticle nippers. Deadly if it swallows air.
Geographic Origin and Distribution
Extensive throughout the Amazon River basin (Brazil, Colombia, Peru). Frequents the banks of large rivers rich in roots and flooded meadows. Never migrates to brackish water.
Origin
Amazon, Orinoco, and Guianas
Fish profile
- Temperament
- Active
- The Amazon Puffer is an active, curious, and schooling species that thrives when kept in groups of three to five specimens. Unlike solitary puffers, they exhibit schooling behavior and are constantly swimming and exploring the tank. They can become stressed and pace the glass if kept alone or in too small a tank.
- Diet
- Carnivore
- They are carnivores that require hard-shelled foods to naturally wear down their rapidly growing teeth. Their diet must include live snails, unshelled shrimp, clam pieces, and crabs daily. They will not accept dry commercial foods, and failure to provide shelled foods will necessitate manual tooth trimming.
- Life expectancy
- 8-10 years
- In captivity, the Amazon Puffer has a typical lifespan of 8 to 10 years when provided with specialized care. Their longevity depends greatly on maintaining immaculate water quality and feeding a proper diet to prevent tooth overgrowth. Proactive treatment for internal parasites upon import is also crucial for their long-term survival.
- Adult size
- 8 cm
- The catalog's scalar value is 8 cm. The FishBase SPECIES table (v25.04 snapshot) source reports a maximum adult measurement of 12.8 cm for this species, recorded as standard length (SL). The taxonomic record consulted is Colomesus asellus (v25.04); male or unsexed record. These figures are not interchangeable: the first is the profile's editorial reference, whereas the second is a published maximum under a specific measurement convention; differences among sources can reflect sex, population, life stage and measuring method.
- Sex ratio
- Group
- Mixed groups of at least 3-5 specimens. They are extremely social.
- Feeding frequency
- Twice daily
- They should be fed once or twice daily, ensuring they receive hard-shelled prey items as a major component of their meals. Because they have a high metabolism and are constantly active, regular feedings are essential to keep them healthy. Monitor their tooth length closely during feeding times to ensure it remains manageable.
- Bioload
- Medium to High
- Medium-High (high metabolism and meaty wastes)
- Flow
- Strong
- They prefer moderate to strong water flow, which mimics the fast-flowing Amazon river systems they inhabit in the wild. Strong currents encourage their natural active swimming behavior and help keep the water highly oxygenated. Efficient filtration is also required to manage their messy feeding habits.
- Jump risk
- Yes
- The Amazon puffer is known to be an active, curious swimmer that presents a moderate jump risk. Because they constantly patrol the tank and often swim vertically up and down the glass ("glass surfing"), they can accidentally propel themselves over the rim. This is particularly true if they are startled or if the water parameters drop below optimal levels. A tight-fitting lid or mesh top is highly recommended to prevent accidental leaps out of the aquarium.
- Reproduction
- Oviparous
- Reproduction in home aquariums is undocumented and believed to be impossible in captivity. In the wild, they are pelagic spawners that release eggs into river currents, which wash the larvae downstream to floodplains. The complex environmental cues and migratory patterns cannot be easily replicated in a home setup.
- Compatibility & tankmates
- With caution
- They are one of the few community-safe pufferfish and can be kept in mixed groups or with fast-swimming tankmates like tetras and barbs. However, they are notorious fin-nippers and should not be housed with slow-moving or long-finned species. They will also hunt and consume any ornamental shrimp or snails in the tank.
- Tank level
- Middle/Bottom
- Amazon puffers are highly active and utilize all levels of the water column, although they favor the mid-to-lower sections for hunting snails and crustaceans. They are constantly on the move, exploring decorations, plants, and the substrate for potential food sources. However, their curious nature frequently brings them to the upper levels, especially when begging for food from their keepers. A well-decorated tank that provides visual barriers across all depths is ideal for keeping them engaged.
Scientific Parameters & Models
FishBase
Window to the official scientific data of the species
Data synced on: 06/15/2026
- Trophic level
- 3.3 ± 0.51 se
- Resilience
- High (less than 15 months)
- Phylogenetic uniqueness (PD50)
- 0.5
- Bayesian Length-Weight
- a = 0.03162, b = 2.86
- VulnerabilityLow vulnerability (10 / 100)
Image gallery
Licensed images linked to the species or, when marked, to the closest representative taxon.
Related species
Recommendations grouped by close relatives, companion choices, and similar care.
