Iguanodectes adujai (GÉRY, 1970)

Etymology

Iguanodectes: from the Taino iwana, meaning ‘lizard’, and Ancient Greek déktés, meaning ‘biter’.
adujai: named for its type locality, the rio Adujá in Brazil.

Classification

Order: Characiformes
Family: Iguanodectidae

Distribution

This species is known from the rio Negro within the Brazilan Amazon basin and upper Río Orinoco system in Venezuela.

Type locality is ‘Rio Adujá, Rio Itú, tributary of middle Rio Negro, Amazonia, Brazil’.

Habitat

There is limited information available on this particular species, but based on what is known, it is believed to inhabit small tributary channels with pristine blackwater. The species’ elongated body shape suggests a preference for flowing water. These habitats are characterized by thick, often overhanging, riparian vegetation, and substrates covered in fallen branches, tree roots, and leaf litter.

The water in these habitats is typically acidic, with low carbonate hardness and conductivity. The water is stained brownish due to the presence of humic substances released by decomposing organic matter. In addition to these habitats, the species may also be associated with “morichals” in the Orinoco system. These habitats typically have transparent, clear water and sandy substrates, often with dense growth of aquatic plants or riparian vegetation among which the fish take shelter.

Maximum Standard Length

The largest specimen known to date measured 62 mm.

Aquarium Size

For the well-being of your fish, we recommend providing them with ample swimming space. An aquarium with a minimum surface area of 90 cm x 30 cm or similar dimensions should be considered.

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Maintenance

To provide the best living conditions for this species, it is recommended to create an aquarium environment that includes a sandy substrate and some driftwood roots and branches. A planted aquarium setup is also suitable for this species. Adding dried leaf litter to the aquarium will not only enhance the natural feel of the environment but also provide additional cover for the fish, as well as bringing the growth of microbe colonies as decomposition occurs.

The growth of microbe colonies is beneficial for the fish, as they provide an additional food source for both adult and juvenile fish. The humic substances released by decaying leaves are also considered beneficial for the overall health of the aquarium. However, it is important to note that the water conditions must be maintained at a high level of quality, as this species is sensitive to poor water conditions. Therefore, it is crucial to avoid introducing this species into biologically immature aquaria.

It is worth noting that the use of natural peat in aquariums is not recommended. The collection of natural peat is both unsustainable and environmentally destructive. Therefore, it is important to provide an appropriate substrate, which may include a layer of nutrient-rich soil covered with sand or gravel.

To maintain a healthy environment, it is recommended to perform regular water changes and provide good filtration. This species does well with a neutral to slightly acidic water pH, with a range between 6.0 and 7.5, and a temperature range of 72°F to 82°F (22°C to 28°C). Adding live plants to the aquarium can also help to maintain water quality, as they provide natural filtration and help to absorb excess nutrients.

In summary, creating a suitable aquarium environment for this species involves providing a sandy substrate, driftwood roots and branches, dried leaf litter, and good filtration. The water should be maintained at a high level of quality, with a neutral to slightly acidic pH, and a temperature range of 72°F to 82°F (22°C to 28°C). Adding live plants to the aquarium can also help to maintain water quality. With proper care and attention, this species can thrive in a well-maintained aquarium environment.

Water Conditions

Temperature: 20 – 26 °C
pH: 5.0 – 7.0
Hardness: 18 – 90 ppm

Diet

It is probable that this species has an omnivorous diet, consuming small invertebrates, crustaceans, filamentous algae, fallen fruit, and similar items in its natural habitat. Although it can subsist on dried food in aquariums, it thrives when provided with a diverse array of sustenance. For optimal health, it is recommended to incorporate live and frozen chironomid larvae (bloodworm), mosquito larvae, Daphnia, Moina, and other suitable prey items into its diet.

bloodworm

Bloodworms are a type of aquatic worm that are widely used as a food source for various aquatic animals, including fish, amphibians, and invertebrates. These small, red worms are a popular choice for aquarium owners and fish breeders as they are nutrient-rich and can help promote healthy growth and development in fish.

The scientific name for bloodworms is Glycera dibranchiata, and they are typically found in freshwater environments such as ponds, lakes, and streams. These worms can range in size from just a few millimeters to several centimeters in length, depending on their age and the specific species.

One of the most interesting features of bloodworms is their bright red coloration. This is due to the presence of hemoglobin in their body, which is a protein that is also found in human blood. Hemoglobin helps to transport oxygen throughout the body and is a crucial component in the respiratory system of these worms.

In the wild, bloodworms feed on a variety of organic matter, including decaying plant material and small aquatic invertebrates. They are also known to be scavengers, feeding on the remains of dead animals and other organic matter found on the bottom of bodies of water.

For aquarium owners, bloodworms are a convenient and affordable source of food for their fish. They can be purchased either live or frozen, with frozen bloodworms being the more common option. Frozen bloodworms can be stored in a freezer for several months and thawed out as needed, making them a convenient and long-lasting food source.

When feeding bloodworms to fish, it is important to ensure that the worms are of an appropriate size for the fish in question. Some fish species may struggle to consume larger bloodworms, while others may require a more substantial meal. It is also important to avoid overfeeding, as this can lead to health problems for the fish and an increase in waste in the aquarium.

In addition to their use as a food source, bloodworms also have a number of other applications. They are sometimes used in scientific research as a model organism, and their unique respiratory system has been the subject of numerous studies. Bloodworms are also sometimes used in composting and vermiculture, as they can help break down organic matter and enrich soil.

In conclusion, bloodworms are a fascinating and versatile organism that have a variety of applications in the aquarium hobby and beyond. Whether you are looking to provide your fish with a nutritious and convenient food source or are interested in learning more about the physiology and ecology of these unique worms, bloodworms are definitely worth exploring.

Behaviour and Compatibility

This species is generally peaceful and can make an excellent addition to a well-planned community aquarium. For optimal results, it is recommended to keep this fish alongside similarly-sized characids, gasteropelecids, lebiasinids, smaller callichthyid or loricariid catfish, and non-predatory small-to-medium-sized cichlids.

To create a more natural-looking environment, it is suggested to purchase a mixed-sex group of at least 8-10 specimens, along with other schooling fish to provide a sense of security. Observing the interaction between rival males is particularly fascinating, as they will display their most vivid colors while competing for female attention or to establish their place in the group’s hierarchy.

To minimize aggression and ensure a harmonious community, it is recommended to purchase more females than males, if possible, to avoid individuals being excessively harassed.

Notes

Iguanodectes adujai is a small, colorful fish that is often exported for the aquarium hobby. It is similar in appearance to its congener Iguanodectes geisleri, but can be distinguished by several characteristics. For instance, I. adujai lacks the black lateral stripe that is present in I. geisleri beneath the red stripe on the body. Additionally, the anal-fin origin is located beneath the dorsal-fin, whereas it is posterior to the dorsal-fin in I. geisleri. The dorsal-fin origin in I. adujai is also posterior to midbody, while in I. geisleri it is at midbody. Finally, I. adujai possesses 28-34 anal-fin rays, compared to 20-25 in I. geisleri.

Both I. adujai and I. geisleri have been traded under the common name of “red line lizard tetra”. Iguanodectes is a relatively small genus with less than ten species, and no new additions have been made since the early 1990s. It is included in the family Iguanodectidae alongside the related genus Piabucus. Piabucus is distinguished from Iguanodectes by the possession of enlarged pectoral fins and a prominent pectoral keel.

The grouping of Iguanodectidae and Piabucus was previously considered to represent a subfamily, Iguanodectinae, prior to phylogenetic analyses conducted by Moreira (2002) and Mirande (2010). The monophyly of the group was evidenced much earlier by Vari (1977). All iguanodectids possess a number of shared characteristics. For example, they have an elongate body, basally-contracted and multicuspid teeth, and gill membranes that are united and free from the isthmus. The posterior end of the maxilla does not extend to the eye, and the dorsal-fin origin is normally positioned posterior to midbody (with the exception of Iguanodectes geisleri, in which it is at midbody). The anal-fin is also long in all species except for I. geisleri. Additionally, there is a process on the internal face of the dentary, the first proximal anal-fin pterygiophore is expanded and recurved posteriorly (except in I. geisleri), and the anterior portion of the posterior swimbladder chamber is thinner than the posterior portion (Moreira in Reis et al. 2003).

References

Géry, J., 1970 – Amazoniana 2(4): 417-433
Le genre Iguanodectes Cope (Pisces, Characoidei).
Cope, E. D., 1872 – Proceedings of the Academy of Natural Sciences of Philadelphia v. 23: 250-294, Pls. 3-16
On the fishes of the Ambyiacu River.
Géry, J., 1977 – T. F. H. Publications, Neptune City, New Jersey: 1-672
Characoids of the World.
Mirande, J. M., 2010 – Neotropical Ichthyology 9(1): 385-568
Phylogeny of the family Characidae (Teleostei: Characiformes) from characters to taxonomy.
Moreira, C. R., 2002 – Unpublished Master Dissertation, Universidade de São Paulo, São Paulo: 276 p.
Relações Filogenéticas em Iguanodectinae (Teleostei; Characiformes; Characidae).
Reis, R. E., S. O. Kullander and C. J. Ferraris, Jr. (eds), 2003 – EDIPUCRS, Porto Alegre: i-xi + 1-729
Check list of the freshwater fishes of South and Central America. CLOFFSCA.