Hoplisoma axelrodi
Hoplisoma axelrodi was first described by Rössel in 1962. They belong to the Callichthyidae family, known as the armored catfish. The genus name Hoplisoma is derived from the Greek words ‘hoplon’ (weapon) and ‘soma’ (body), referring to the armor of these fish. The species name axelrodi is in honor of Dr. Herbert Axelrod, a well-known ichthyologist and publisher. There is no specific Dutch name for this fish species, but it is often referred to as Axelrod’s Corydoras or Pink Corydoras.
The synonym for this species of fish is Corydoras axelrodi.
Description
Body Shape and Color
Hoplisoma axelrodi has a compact and streamlined body shape. The fish has a pale, almost pink base color with a striking black vertical band running through the eyes and two lateral bands along the body. The upper band is thicker and more prominent than the lower one. The fins are generally translucent, with the dorsal fin appearing darker at the base.
Size
This species reaches a maximum length of about 4.2 cm.
Differences between Males and Females
Females are usually larger and have a rounder and broader body, especially when carrying eggs. Males are usually smaller and have a slimmer stature.
Behavioral differences
No specific behavioral differences between the sexes have been reported, but females may be more active during the mating season because of their role in laying eggs.
Behavior and Temperament
Hoplisoma axelrodi is a peaceful and social fish best kept in groups of at least 6-8 individuals. They are not aggressive and get along well with other peaceful species. These fish are bottom dwellers and spend most of their time searching for food on the bottom of the aquarium.
Character
They are generally not shy and exhibit a curious behavior, especially when kept in a group.
Life expectancy
In the wild, these fish can live for several years, but in a well-maintained aquarium they can live up to 6 years.
Breathing above water
Hoplisoma axelrodi is a facultative respirator. This means that the fish is able to extract oxygen from the water via the gills as well as directly from the air. This ability is particularly useful in environments where oxygen levels in the water can be low.
Mechanism of Facultative Breathing
- Air Breathing: Axelrod’s Corydoras has an adapted, highly circulatory intestinal system that can absorb oxygen from the air. The fish swims to the water surface to swallow air, which is then directed to the intestines where the oxygen is absorbed.
- Benefits: This breathing method allows fish to survive in oxygen-deficient conditions, such as stagnant or polluted water. It provides an evolutionary advantage in habitats where water quality fluctuates.
- Behavior: In the aqu arium, this behavior can be observed when the fish rise to the surface to gasp air. This is normal and no cause for concern, unless it occurs very frequently , which may indicate a water quality problem.
Facultative respiration is a fascinating adaptive mechanism that contributes to the survival of Hoplisoma axelrodi in diverse aquatic environments.
Biotope
Distribution and Habitat.
Hoplisoma axelrodi, also known as Axelrod’s Corydoras, is native to South America, specifically Colombia. They are endemic to the Meta River basin.
These fish are river fish and live mainly in the Meta River, which flows through Colombia. Their natural habitat consists of clear, flowing waters with a sandy or fine gravel bottom. The area is often rich in underwater vegetation and surrounded by trees, providing shade and shelter.
Soil and Substrate
The bottom of their natural habitat consists mainly of fine sand or smooth gravel, which is ideal for their foraging behavior.
Climate and Seasonality
Hoplisoma axelrodi lives in a tropical climate with stable temperatures between 22°C and 26°C. There are no specific records of seasonal floods or droughts, but the rivers in their habitat may experience variations in water levels depending on the season.
Diet
Diet in the Wild
Hoplisoma axelrodi is an omnivore. In the wild, this fish feeds on a variety of food sources, including small invertebrates, insect larvae, and plant material found on the bottom of their natural habitat.
Food in the Aquarium
In the aquarium, Axelrod’s Corydoras can be fed a varied diet to promote their health and vitality. They readily accept sinking dry foods such as tablets, granules, and larger flakes. In addition, live or frozen foods such as mosquito larvae, tubifex, and daphnia are excellent choices to supplement their diet. It is also helpful to enrich their diet with vegetable matter such as blanched spinach or zucchini.
What Not to Feed
It is important to avoid feeding Axelrod’s Corydoras exclusively on scraps from other aquarium inhabitants, as this does not provide sufficient nutrients. Also, they should not be expected to keep the aquarium clean by living only on scraps.
The Aquarium
Aquarium size
To keep Hoplisoma axelrodi, also known as Axelrod’s Corydoras, an aquarium of at least 76 liters is recommended. If you want to keep several pairs, a larger aquarium is recommended to provide enough space for their social behavior and to minimize stress.
The Aquarium
Substrate
The best substrate for this species is fine sand. Sharp coarse gravel or sharp sand are not recommended because debris can accumulate among the gravel. If the fish damage their beard threads while foraging, the debris can cause the wounds to inflame, which can lead to loss of the beard threads. Over time, however, these may grow back if kept on rounded sand.
Aquarium Setup
The aquarium should be set up with plenty of hiding places, such as pieces of driftwood and dense plantings. This provides safety for the fish and encourages their natural behavior. Provide open swimming areas and shaded areas with overhanging rocks or driftwood.
Water parameters
Ideal water conditions for Hoplisoma axelrodi are a temperature between 22°C and 26°C, a pH of 5.5 to 7.5, and hardness of 2 to 25 dH.
Suitable Tank Mates
Hoplisoma axelrodi is a peaceful and social fish that lives well with other peaceful species. Suitable co-inhabitants are small to medium-sized cyprinids, carp salmon, gouramis, and dwarf cichlids. Avoid keeping them together with larger or aggressive species, as this can lead to stress and intimidation.
Breeding aquarium and conditioning
Hoplisoma axelrodi can be bred in either an ordinary aquarium or a dedicated breeding aquarium. However, a dedicated breeding aquarium is often recommended for optimal results.
Species Breeding Aquarium
- Size: A breeding aquarium of about 40 to 60 liters is suitable.
- Water quality: The water should be soft and slightly acidic, with a pH between 6.0 and 7.0 and a temperature of 22°C to 26°C.
- Lighting: Keep lighting dimmed to mimic a natural environment.
- Filter: Use a soft sponge filter to maintain water quality without disturbing eggs or young fish.
Conditioning the Fish
Diet
The fish are conditioned with a varied diet of live and frozen foods such as mosquito larvae, tubifex, and daphnia. This helps to put the fish in optimal condition for breeding.
Separation and Amalgamation
It is common to temporarily separate males and females and then reunite them in the breeding aquarium to encourage spawning.
Breeding Group
A typical breeding group consists of a ratio of two males per female. This increases the likelihood of successful fertilization of the eggs.
The Spawn
Colors during spawning
During mating , the colors of Hoplisoma axelrodi, also known as Axelrod’s Corydoras, may become more intense. This is a common phenomenon in many fish species, where the colors become more vivid to attract mates and deter competitors.
Courtmaking Ritual
The courting ritual of Axelrod’s Corydoras often begins with the male approaching the females and trying to seduce them by swimming around them and spreading his fins. This behavior may be accompanied by light vibrations and touching the females with his snout.
Laying the Eggs
T-position and Fertilization
During deposition, the fish adopt the characteristic T position. In this position, the female places her head against the male’s flank, allowing the male to release his sperm. The sperm reaches the eggs that the female holds between her ventral fins.
Eggs and Laying Process
The eggs are usually deposited on smooth surfaces such as aquarium glass, plant leaves or specially placed deposit mops. Mating often takes place in the morning, although it can also occur at other times of the day.
Axelrod’s Corydoras are egg-layers and the eggs are laid open and exposed, often in a spot carefully selected by the female. The female holds 2-4 eggs between her ventral fins, where the male fertilizes them. Then the female swims to a suitable spot to attach the sticky eggs. This process is repeated until about 100 eggs have been deposited. They usually deposit the eggs in a place where current hits a flat surface. You can help them a bit by temporarily aiming a flow pump at a spot on the aquarium glass.
Number, Size and Color of Eggs
Approximately 100 eggs are laid. The eggs are small and translucent to pale yellow in color. They are very sticky, which helps keep them in place on the chosen substrate.
Raising the fry
The eggs of Hoplisoma axelrodi usually hatch after an incubation period of 3 to 4 days. After hatching , it takes another 2 to 3 days for the young to fully absorb their yolk sacs and begin to swim freely.
There is no parental care in Hoplisoma axelrodi. After the eggs are deposited, the parents are not engaged in caring for the young and may even eat the eggs if they are not removed.
First food
Once the young begin to swim freely, they can be fed small live foods such as microworms and Artemia nauplii. It is important to feed them small amounts several times a day to support their growth and development.
Water change
Regular water changes are crucial for the well-being of young fish. It is recommended that about 20-30% of the water be changed weekly to keep water quality high and prevent the buildup of pollutants.
Particularities
Taxonomic History: The species was originally described as Corydoras axelrodi, but is now classified under the genus Hoplisoma. This is a result of taxonomic revisions within the family Callichthyidae, in which the short-beaked species of Corydoras were transferred to Hoplisoma.
Video
Author
John de Lange
Copyright images
Hristo Hristov
Michael Negrini – Pisciculture d’Estalens (original website no longer online)
