Spotted Hatchetfish

In the wild, the Spotted Hatchetfish typically grows up to 6 cm in length. However, in aquariums, under favorable conditions and without predators, some individuals can reach 8–9 cm. Their body shape is characteristic of hatchetfish: the belly is strongly developed, resembling the keel of a ship or the blade of an axe. In appearance, size, and silvery coloration, the Spotted Hatchetfish is similar to the Platinum Hatchetfish, but it is distinguished by the presence of dark speckles. Sexual dimorphism in these fish is weakly expressed; adult males and females are practically indistinguishable. Only during the spawning period may females appear somewhat distended due to eggs.

This fish is found in the waters of South and Central America. Its natural range includes Panama and eastern Colombia, where it inhabits river systems flowing into the Pacific Ocean. It prefers to live in small streams and rivers, staying near the water surface, in the upper layer. It is most often seen near plant clusters, under overhanging foliage, and among other potential hiding places.

This peaceful and active fish prefers to live in large groups. It is recommended to acquire at least 8–10 individuals. It is well compatible with most calm fish species of comparable size. Fish that inhabit the middle or bottom layers of the aquarium would be an excellent choice.

As mentioned, Gasteropelecus maculatus spends most of its time in the surface layer of the water. Therefore, when setting up an aquarium, the main emphasis should be on the upper stratum, providing sufficient free space for swimming and several hiding places. Plants reaching the surface can serve as such shelters. The decoration of the lower stratum is not significantly important for this species. The optimal aquarium volume for a group of 8–10 fish starts from 250 liters; in this case, the surface area of the water plays a more important role than the depth. Hatchetfish tolerate excessive current poorly. The main source of water movement in the aquarium is the filter, so a model capable of providing a relatively calm, non-turbulent environment should be chosen. The fish prefer soft, slightly acidic water and require a warm, well-oxygenated environment, which sometimes necessitates additional aeration. The daily diet should be based on protein-rich foods that float on the surface. Foods that sink to the bottom will likely be ignored by the fish.

The basis of the daily diet should consist of foods that float on the surface and contain sufficient protein. Food that sinks to the bottom is generally ignored by these fish.

Breeding is considered a challenging task and requires a separate spawning tank of at least 50 liters. The water should be soft and slightly acidic, with a pH of 5.5–6.5 and a temperature of about 25 °C. To stimulate spawning, the breeders are fed abundantly with live foods such as mosquito larvae or Artemia nauplii. Fine-leaved plants or floating vegetation are placed in the spawning tank, among the roots of which the fish lay their eggs. After the process is complete, the breeders must be removed, as they are prone to eating the eggs. Larvae hatch after 30 hours, and on the fifth day, the fry begin to swim freely and require infusoria or the finest starter food.

The species is sensitive to water quality and is susceptible to typical characin diseases if kept in improper conditions. The main problems arise from the accumulation of organic matter, which can lead to bacterial infections or fin rot. The fish react extremely negatively to sharp fluctuations in environmental parameters and chemical preparations containing copper or aggressive dyes. Prevention involves maintaining stable parameters, regular water changes, and ensuring high oxygen content. When stressed or in poor conditions, the fish become susceptible to Ichthyophthiriasis.

When purchasing, attention should be paid to the activity of the fish and the integrity of their fins. Healthy individuals should stay in a school in the upper water layers and show interest in the surface. Avoid specimens with damaged scales, film on the body, or an unnaturally sunken belly. It is important to ensure that the fish show no signs of emaciation, as hatchetfish tolerate prolonged starvation or stress during transport poorly. It is recommended to acquire a group of 6 or more individuals to reduce timidity, as single fish in a store are often under severe stress.