Gasteropelecus maculatus

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Gasteropelecus maculatus, also known as the Spotted Silver Hatchetfish, is a small South American characin recognized by its silvery body, greatly enlarged pectoral fins, and dark markings. Native to the Magdalena River basin in Colombia, it inhabits calm areas close to the surface, where its body shape allows it to move quickly just beneath the water film. Peaceful and shoaling, it does best in a group in a tightly covered aquarium with warm, soft to slightly acidic water and moderate circulation. It remains relatively uncommon in the aquarium trade, making it an interesting choice for keepers of surface-dwelling fishes. This profile concerns specimens collected in the wild.

General species description

Gasteropelecus maculatus belongs to the family Gasteropelecidae, a group commonly known as hatchetfishes. Its deep, laterally compressed body and upturned mouth reveal a strong adaptation to surface life. The species is peaceful, but it should be kept in a group of at least six individuals to reduce stress and encourage natural behavior. It mainly occupies the upper part of the aquarium and may leap when startled, so a securely fitted lid is essential. It suits a calm community aquarium without large or predatory tank mates.

Geographic origin and biotope

Reference country: Colombia. Gasteropelecus maculatus is associated with the Magdalena River basin in northwestern South America. Its habitat includes freshwater with low to moderate flow, particularly quiet margins, small channels, and areas sheltered by shoreline vegetation. The surface receives filtered light, while branches, roots, and emergent plants provide cover from predators. In an aquarium, an open surface area, some floating plants, and filtration without excessive turbulence reproduce its habits more effectively than a highly agitated layout.

Precise location and local name

The species is linked to the Magdalena drainage basin in Colombia, where it is associated with slow-moving water and sheltered peripheral areas of this extensive river system. The English common name Spotted Silver Hatchetfish is the most useful name in the international aquarium trade. In French, “poisson-hachette argenté tacheté” accurately describes its appearance, but it is a descriptive translation rather than a broadly established common name. Its restricted northern South American distribution helps explain why it is less common in stores than several other hatchetfishes.

Appearance and physical characteristics

The body of Gasteropelecus maculatus is short, very deep, and strongly compressed, with an arched belly that creates the typical hatchetfish outline. The overall coloration is silvery and reflective, marked with dark spots that explain the specific name maculatus. The pectoral fins are long and positioned high on the sides, helping the fish make rapid movements near the surface. The dorsal fin is set far back, while the upturned mouth assists with taking floating prey. Its size is modest, but its profile calls for a longer aquarium rather than a very tall one.

General diet

In the wild, Gasteropelecus maculatus mainly feeds on small prey taken from the surface, including terrestrial insects falling onto the water, small aquatic insects, and other tiny organisms. In aquaria, it accepts small floating foods such as micro pellets, flakes, daphnia, brine shrimp, and mosquito larvae from a safe source. Several small feedings per day are preferable to one large meal. Food that sinks quickly may be ignored. A varied diet containing frozen or live prey helps maintain its condition and silvery coloration.

Essential data

• River of origin: Magdalena River
• Local name used: Spotted Silver Hatchetfish
• Origin of the scientific name: Gasteropelecus is the genus name assigned to hatchetfishes; maculatus describes the species.
• Full-name etymology: Gasteropelecus comes from the Greek gaster, belly, and pelekys, axe; maculatus comes from Latin and means spotted.
• Common/vernacular names: Spotted Silver Hatchetfish; spotted silver hatchetfish.
• Family: Gasteropelecidae
• Subfamily: Gasteropelecidae; no commonly used subfamily is retained.
• Name pronunciation: gas-ter-oh-PEH-leh-kus - mah-kuh-LAH-tus
• Discovery: Franz Steindachner, 1879
• Maximum adult size: About 7 cm
• Water temperature and pH: 24 to 28 °C; pH 5.5 to 7.0
• Watercourse appearance and surrounding vegetation: Calm to moderately flowing water, shaded margins, roots, branches, and shoreline or floating vegetation.
• Typical tank mates: Geophagus steindachneri; Caquetaia kraussii; peaceful small characins; small non-aggressive loricariids.
• Temperament and behavior: Peaceful, shoaling, and active near the surface; may jump when stressed.
• Water depth: Surface and upper areas of calm water.
• Sexual dimorphism: Mature females are generally stockier and deeper-bodied; sexing can be difficult outside the breeding period.
• Bottom structure and flow: Sandy or muddy substrate, often covered with plant debris; low to moderate flow in occupied areas.

In your aquarium

Successful care of Gasteropelecus maculatus requires a tightly covered aquarium, stable water, and a properly sized group. Leave an open surface area, add some floating plants, and avoid boisterous tank mates. Efficient but gentle filtration, together with varied small floating meals, supports natural behavior. Since this is a wild-collected species that is relatively uncommon, gradual acclimation and careful quarantine are especially advisable.