Threadfin Rainbowfish (Iriatherina werneri)

Origin

The Threadfin Rainbowfish’s origins can be traced back to Indonesia’s shallow rivers and streams, where they can be found in the wild. This species is unique to the region and is not found anywhere else in the world. The Threadfin Rainbow thrives in Indonesia because of its tropical climate and lush vegetation. In addition to its natural habitat, it has been introduced to other parts of the world, including Australia, Europe, and the Americas, where it has become a popular aquarium species. 

Appearance & Size

Threadfin Rainbow is distinguished by its iridescent scales, which give them a rainbow-like appearance. Their bodies can be silvery blue to green, with bright red and yellow accents on their fins and tail. The Threadfin Rainbow is also named after its long, flowing dorsal fin, which resembles a thread. Furthermore, the Threadfin Rainbow has a slender and graceful body shape.

The size of the Threadfin Rainbow is relatively small, typically growing to about 4-5 cm long.

Genders

The Threadfin Rainbow is a sexually dimorphic species, which means that males and females look very different. Males are usually brighter in color and have more vibrant finnage than females. Male Threadfin Rainbows have a more prominent and elongated dorsal fin. Female Threadfin Rainbows, on the other hand, have a rounder body shape and are slightly larger. 

Behavior

The Threadfin Rainbow is a peaceful and graceful species known for its calm behavior. These fish are active swimmers who enjoy exploring their surroundings but are not aggressive to other fish. They are most active during the day but become less active at night.

Tankmates

When selecting tankmates for the Threadfin Rainbow, choosing species with similar water requirements and peaceful behavior is important. These fish are not aggressive and do well in community aquariums if their tankmates are non-aggressive. 

Here is a list of good tankmates for the Threadfin Rainbow:

• Other peaceful community fish, such as Neon Tetras, Guppies, and Mollies
• Shrimp and snails, such as Amano Shrimp or Nerite Snails
• Small, peaceful bottom-dwelling fish such as Corydoras Catfish
• Other rainbowfish species, such as the Boeseman’s Rainbowfish or the Lake Kutubu Rainbowfish

Tank conditions

The Threadfin Rainbow is a tough species that thrive in captivity, but proper tank conditions are critical to their health and well-being. These fish are native to Papua New Guinea’s slow-moving rivers and streams, and they prefer a well-established aquarium with a soft and sandy substrate, plenty of hiding places, and plenty of water flow. 

The water temperature should be between 72 and 82 degrees Fahrenheit, with a pH range of 6.0 to 7.5 and a moderate to high water hardness. To keep the aquarium clean and healthy, providing them with a filtration system capable of maintaining stable water conditions is critical. 

Ample lighting also benefits Threadfin Rainbow health because it promotes the growth of aquatic plants and other organisms that are a natural part of their diet. A minimum of 10 gallons is recommended for a single fish, but a larger tank is required if you intend to house multiple Threadfin Rainbows together. 

Diet

The Threadfin Rainbow is an omnivorous species that eats various foods. They eat small insects, crustaceans, and plant matter in the wild. They can be fed a varied diet of meaty and plant-based foods in the aquarium.

High-quality dry foods like flake food or pellets and frozen or live foods like brine shrimp, bloodworms, and daphnia can make up a good staple diet for the Threadfin Rainbow. They will also benefit from feedings of fresh or frozen fruits and vegetables such as spinach, peas, and zucchini regularly.

It is critical to avoid overfeeding the Threadfin Rainbow, as this can cause water quality issues and harm the fish’s health. A well-balanced diet and consistent feeding schedule will help to ensure your Threadfin Rainbow’s overall health and longevity. Feed the Threadfin Rainbow small amounts of food 2-3 times daily, allowing them to consume food within a few minutes. 

Breeding

Breeding Threadfin Rainbows in an aquarium environment can be challenging but is achievable with the right conditions and techniques. These fish are egg-layers and will lay their eggs on flat surfaces in the aquarium, such as rocks or leaves.

Providing Threadfin Rainbows with optimal water conditions, including the proper temperature, pH, and water hardness levels, is critical to encourage breeding. It may also be necessary to mimic their natural habitat by providing plenty of hiding places and vegetation. A varied diet can also help increase the likelihood of breeding. Live or frozen foods, in particular, can stimulate Threadfin Rainbow breeding behavior.

It is also recommended that the breeding tank have a male-to-multiple-female ratio to increase the chances of successful breeding. The males will engage in courtship behavior with the females and may construct bubble nests to protect the eggs until they hatch.

Once the eggs hatch, the parents must be removed from the breeding tank to prevent them from preying on their offspring. The fry will require small, frequent feedings of live or frozen food to ensure their growth and survival.

Diseases

Threadfin rainbows are susceptible to various diseases and illnesses like all other fish species. Pet owners need to be aware of the common conditions that can affect their fish and take necessary steps to prevent them from happening. 

Some of the diseases that Threadfin rainbows are prone to include:

• Ich: Ich is a parasitic infection that manifests as white spots on the fish’s skin and fins. This disease is caused by the parasite Ichthyophthirius multifiliis and is most commonly found in tanks with poor water quality.
• Fin rot: Fin rot is a bacterial infection that causes the fish’s fins to rot and become frayed. This disease can be caused by various factors, including poor water quality, overcrowding, or physical damage to the fins.
• Swim bladder disorder: Swim bladder disorder is when the fish’s swim bladder becomes distended, causing the fish to have trouble swimming. This condition can be caused by overfeeding or physical damage to the swim bladder.

Maintaining good water quality, keeping the tank well-ventilated, and feeding your fish a healthy diet to avoid these and other diseases are critical. If you notice any signs of illness in your Threadfin rainbows, you must act quickly to prevent the disease from spreading to other fish in the tank.