Amazon Puffer

Geographical Origin & Biotope:

*Colomesus asellus* boasts an incredible and vast distribution in South America. It inhabits the entire Amazon River basin (Peru, Colombia, Brazil) and extends to the Orinoco basin (Venezuela). It lives in fast-flowing rivers and their large freshwater tributaries (it is not found in brackish waters). During the rainy season, it migrates into flooded forests following the currents, feeding on the abundant benthic macro-fauna.

Taxonomy & Morphology:

Belonging to the Tetraodontidae family. It is the only strictly freshwater species of its genus in South America (its cousin *C. psittacus* is brackish and much larger). The body morphology is that of a small submarine, highly hydrodynamic compared to sedentary Asian Puffers, with powerful pectoral fins. Adults reach 8-10 centimeters (3-4 inches).

Social Behavior:

They are the worker bees of the aquarium. Extremely hyperactive, intelligent, and incredibly sociable towards their own kind (an absolute rarity in the family). They will incessantly swim up and down, often following each other in single file, patrolling leaves and stones. Solitude terrifies them: without companions *of their species*, they will spend all their time neurotically swimming against the glass, often refusing food.

Coloration & Sexual Dimorphism:

The dorsal coloration is a lively and very pleasant ochre yellow or bright yellow-green. On this golden background stand out 5 sharp, saddle-shaped black transverse bands that cross the back from side to side, making them look like tiny "aquatic bees". The belly is strictly pure white. They exhibit no visible sexual dimorphism.

Tank Setup:

Unlike their ambush-hunting Asian cousins, the Amazon Puffer is a tireless river swimmer. The aquarium must be long (minimum 100 cm / 3 feet, 150-200 liters / 40-55 gallons) and horizontally oriented to allow them to patrol in a school. The setup must include plenty of wood (bogwood, intricate roots) and wide open swimming areas. A fundamental characteristic is oxygenation and current: being river fish, they love swimming against the current (the use of a powerhead is recommended). It strictly does not tolerate solitude: it *must* be kept in schools of 3-6 specimens. If kept alone or in a bare tank, it will fall into severe neurological stress known as "glass surfing", frantically swimming up and down against the glass until exhaustion.

Diet & Feeding:

This is where the "Expert" classification lies. This species holds the world record for dental growth among freshwater pufferfish. The bony beak grows with frightening rapidity. They must eat crustaceans and hard snails (Physa, Assassin snails, Melanoides) literally every single day. Despite this, in 90% of cases, the diet is not enough to wear down the teeth. Within a year, the aquarist will have to catch the fish, lightly anesthetize it in a container with clove oil (eugenol), and gently file or clip its teeth with cuticle nippers; otherwise, the beak will fuse shut, condemning it to starve. It is a mandatory surgical operation for those who own this fish.

Water Quality:

Strictly freshwater. The South American rivers from which it comes are soft and neutral/acidic (pH 6.0-7.5, GH 2-15). They are intolerant to nitrate accumulation, and lacking scales, they react very poorly to common copper-based medications, so the water must be kept chemically perfect through oversized filtration and copious 50% weekly water changes.

Compatibility & Tankmates:

The joy of owning a *C. asellus* is being able to put it in a South American community aquarium. Unlike almost all other Puffers, it is not a psychopathic killer: it is not territorial, it doesn't tear tankmates to pieces, and it swims peacefully alongside large Tetras, Corydoras, and Plecos. However, boredom or hunger can turn them into fin nippers: avoid slow fish or those with long trailing fins (Angelfish, Bettas, Guppies). Any ornamental shrimp (Amano or Neocaridina) will instead be considered an expensive delicacy.

Aquarium Breeding:

Totally impossible for the hobbyist. This species (unique among river puffers) lays tiny, non-adhesive eggs that rely on the strong current of the Amazon River to be dispersed as pelagic eggs along the river basin. All specimens on the market are, by necessity, wild-caught.

Risks & Diseases:

The home surgical operation of "filing" the beak (fish dentistry) represents the greatest lethal risk if you do not know how to manage sedative doses. Secondly, wild imports very often arrive infested with intestinal worms (Nematodes) and gill flukes. A treatment in a quarantine tank with deworming medication is the only way to get them back in shape. Never forget: if scared, Puffers inflate, but if they do so by swallowing air *out* of the water, they may not be able to expel it, suffocating to death.