Hoplisoma schwartzi
Hoplisoma schwartzi was first described by Rössel in 1963. This fish belongs to the family Callichthyidae. The family Callichthyidae consists of about 200 species divided into nine genera. The genus Hoplisoma was introduced in 1838 by the English naturalist William Swainson, but was later synonymized with Corydoras and redescribed and validated in June 2024. The genus Hoplisoma includes short-nosed species that previously belonged to Corydoras.
The genus name Hoplisoma is derived from the Greek ‘hoplon’ (weapon) and ‘soma’ (body), referring to the fish’s armor. The species name schwartzi is in honor of the exporter Willy Schwartz.
Synonym: Corydoras schwartzi.
Description
General description:
Hoplisoma schwartzi has a robust, rounded head and a body that varies from bright white-cream to gray with occasional spots on the fin membranes. The fish has a distinctive black spot just below the dorsal fin, which can vary in size and shape. The fish grows to about 5 centimeters in length.
Differences between males and females:
Females are usually larger and rounder than males of the same age. No specific behavioral differences between the sexes have been reported.
Behavior and temperament:
Hoplisoma schwartzi is a peaceful fish that likes to live in groups. They are bottom dwellers and like fine sand as a substrate. They are social and shy, but quickly lose their shyness in a well-equipped environment.
Life expectancy:
In a well maintained aquarium, they can live 3 to 5 years.
Hoplisoma schwartzi, also known as Schwartz’s Panzerwels, is a species of fish belonging to the family Callichthyidae. These fish have an interesting feature that helps them survive in their natural habitat: facultative air breathing. This means that they are able to breathe atmospheric air when oxygen levels in the water are low.
Facultative Air Breathing
Hoplisoma schwartzi uses a well-vascularized intestinal tract as an additional respiratory organ. This allows them to swallow air from the water surface and absorb oxygen through their intestines. The oxygen is then transported through the blood, while the used air is expelled through the anus.
Benefits of Air Breathing:
- Survival in Low-Oxygen Environments: This trait is particularly useful in their natural habitat, such as the Rio Purus in Brazil, where waters are often low in oxygen, especially during the dry season when water levels drop and fish populations become concentrated in small bodies of water.
- Reduction of Ammonia Toxicity: Research has shown that air-breathing can reduce ammonia toxicity. When Hoplisoma schwartzi is deprived of air, ammonia toxicity doubles, suggesting that air-breathing helps to reduce ventilation and perfusion of the gills, thereby limiting the uptake of ammonia from the environment.
Adaptation to Poor Water Quality:
Facultative air-breathing is a common adaptation in many Amazonian fish that live in areas with poor water quality. This ability allows them to survive in conditions where other fish might not.
The facultative air breathing of Hoplisoma schwartzi is a crucial adaptation that helps them survive in oxygen-poor and ammonia-rich environments. This makes them particularly suited to life in the dynamic and often challenging waters of the Amazon. This trait is not only fascinating from a biological perspective but also important for aquarists who wish to keep this species in captivity, as it provides insight into the specific needs and behaviors of these fish.
Biotope
Natural distribution:
Hoplisoma schwartzi is native to Brazil, mainly in the Rio Purus basin.
Habitat:
They live in rivers and streams with little underwater vegetation, but the banks are often covered with trees. The soil is usually fine sand. They live in a tropical climate with seasonal flooding.
Diet
Diet in the wild:
In the wild they feed on small invertebrates such as worms and insects.
Diet in the aquarium:
In the aquarium they can be fed live food, frozen food and dry food. They like to eat algae wafers and sinking shrimp pellets.
The Aquarium
Aquarium size:
An aquarium of at least 80 centimeters is suitable for a group. For multiple pairs, a larger aquarium is recommended.
Decoration:
The aquarium should be decorated with fine sand as a substrate to protect their sensitive barbels. Overhanging roots and rock shelters are ideal. A cover of floating plants contributes to their well-being.
Water parameters:
The best water parameters are a temperature of 24-28°C, a pH of 6.0-7.0 and soft water.
Compatibility:
They can live well with peaceful fish such as tetras, guppies and other small, non-aggressive species.
Breeding aquarium and conditioning
Breeding aquarium:
For breeding Hoplisoma schwartzi a special breeding aquarium is recommended. An aquarium of 45x30x30 cm (approximately 40 liters) is suitable. The aquarium should be set up with a fine sand or gravel substrate and some hiding places such as pieces of bogwood or Java moss. Use an air-driven sponge filter to prevent the fry from being sucked in and to create a gentle water flow.
Water Quality:
Water quality is crucial for successful cultivation. The temperature should be around 23-25°C, with a pH of around 6.5-7.0 and a hardness of 1-5°dGH. Using reverse osmosis (RO) water and filtering the water through peat can help achieve the right water conditions
Lowering the Water Temperature
A common method to encourage the spawning of Hoplisoma species is to lower the water temperature. This simulates the conditions of the rainy season in their natural habitat, which is often a trigger for spawning. Perform a large water change (50-70%) with water that is a few degrees colder than the aquarium water. This can lower the temperature by 2-3°C and encourage the fish to start breeding.
Breeding conditions:
For breeding a special breeding aquarium of 45x30x30 cm is recommended, with a temperature of about 24°C and a pH of 6.5. Use an air-driven sponge filter and add some Java moss . Condition the fish with a varied diet of live, frozen and dry food.
Conditioning the Fish
Diet:
Conditioning your fish is essential for successful breeding. Feed your fish a varied diet of live, frozen and dry foods. Live foods such as bloodworms, white worms, grindal worms, Daphnia and Tubifex are particularly effective in keeping your fish in top condition.
Separating the Sexes:
It may be helpful to temporarily separate the males and females and then re-introduce them for breeding. This increases the chances of successful fertilization. A ratio of two males to one female is recommended to encourage competition between males and increase the chances of fertilization. A ratio of two males to one female is recommended.
The spawn
Courtship Ritual and T-Position:
The courtship ritual of Hoplisoma schwartzi follows the classic Corydoras formula. The male pursues the female and stimulates her with his barbels. When the female is ready to lay eggs, they assume the T-position. In this position, the male grasps the female’s barbels between his pectoral fin and body. The male releases sperm, which is guided through the female’s mouth and gills to her pelvic fins. The female’s pelvic fins form a kind of ‘basket’ into which she lays 2 to 4 eggs.
Laying the Eggs:
The eggs are fertilized in the female’s pelvic fin ‘basket’. This process takes about 30 seconds. Once the eggs are fertilized, the female swims to a suitable place to lay the eggs. This can be a smooth surface such as the glass of the aquarium, plants or other decorations. The eggs are very sticky and stick firmly to the surface. The female repeats this process several times until she has laid all her eggs. In total, a female can lay about 100 eggs.
Egg Protection:
It is important to protect the eggs from the adult fish as they may eat the eggs. This can be done by removing the adult fish after spawning or by transferring the eggs to a separate breeding tank. Add a few drops of methylene blue to the water to prevent mold growth on the eggs. Remove any moldy eggs to prevent the mold from spreading. Methylene blue also turns sealant blue and be careful not to get it on your hands. It is not freely available in all countries.
Raising the fry
Hatching and free swimming:
The eggs hatch after about 3-5 days. The fry start to swim freely after a few days. There is no parental care after the eggs hatch. The first food for the fry consists of infusoria and later on artemia nauplii. Water changes should be done regularly to keep the water quality high.
Particularities
Hoplisoma schwartzi is one of the most popular Hoplisoma species in aquariums because of their unique black and white color pattern and peaceful nature. They are also suitable for beginners because of their hardiness and easy care.
Conclusion
Hoplisoma schwartzi is an excellent choice for both novice and experienced aquarists. They are peaceful, social, and relatively easy to care for. Their unique appearance and interesting behavior make them a valuable addition to any community tank. Breeding this species can be challenging, but is very rewarding for the dedicated aquarist.
Video
Author
John de Lange
Copyright images
Andy Gordon (original website no longer available)
