Comprehensive Guide to Paradise Fish (Macropodus opercularis): Care, Habitat, and Tips

Introduction

Macropodus opercularis, commonly known as the Paradise Fish, belongs to the anabantid family. Like Bettas and Gouramis, these fish possess a special organ called the labyrinth organ, which allows them to breathe atmospheric oxygen. This adaptation enables them to thrive in murky and low-oxygen environments where most fish cannot survive. Paradise Fish are renowned for their hardiness and ease of care, making them popular ornamental pets in the freshwater aquarium hobby.

Description

Paradise Fish have an oval, laterally compressed body shape and can grow up to 4 inches (~10cm) in length. They are known for their striking appearance, featuring bright orange and vivid blue vertical stripes. Their long, flowing fins make them a popular choice in the aquarium trade. There are several notable variations of Paradise Fish:

• Albino Paradise Fish: Unlike typical albino fish, this variation retains bright orange stripes but lacks darker hues elsewhere. The stripes may fade when the fish is calm but become more intense when the fish is agitated. The fins are generally clear with iridescent patterns.
• Black Paradise Fish: This variation is light brown with dark-edged scales. It is less aggressive towards other fish except during spawning. Males can be identified by the reddish coloration on their fins.
• Chinese Paradise Fish: Known for their long, attractive fins with bold red and blue patterns, these fish have dark, almost black bodies. Despite their beauty, they are quite aggressive, especially males toward other males.
• Spike-Tailed Paradise Fish: Recognizable by the pronounced spikes on their caudal and anal fins, males have longer spikes and more vibrant colors. They are less aggressive and can be kept in community tanks.
• Day’s Paradise Fish: These fish have lightly colored, almost pinkish bodies with blue fins that darken toward the edges. Males feature a rounded caudal fin with an extended point in the center. This variation is known for its non-aggressive nature, even among males.

Labyrinth Organ

The labyrinth organ is a specialized structure that allows anabantid fish, such as the Paradise Fish, to breathe atmospheric oxygen. This organ consists of lamellae, which are folds of skin lined with numerous tiny blood vessels that facilitate the absorption of oxygen from the air. Located just behind the gills, the labyrinth organ enables the fish to gulp air at the water's surface and transfer oxygen into this organ, while expelling excess carbon dioxide through the gills. Despite their ability to breathe air, Paradise Fish must remain submerged to ensure they stay properly lubricated and hydrated.

Habitat

Paradise Fish are native to Asia, specifically found in the freshwaters of East Asia, the Korean Peninsula, and Northern Vietnam. They thrive in murky, low-oxygen environments where many other fish would struggle to survive. You can find these fish in rice paddies and irrigation ditches, where the water temperature can vary widely but is often warm and oxygen-depleted. Their ability to endure such challenging conditions is a key characteristic of this species.

Water Conditions

Paradise Fish are notably adaptable to a range of water conditions. They can thrive in stagnant, dirty, and low-oxygen water environments - conditions that would be unsuitable for most other fish. In fact, they can even live happily in containers with stagnant water where mosquito larvae are present, feeding on the larvae. Despite their hardiness, optimal conditions for Paradise Fish include a water temperature between 20-26°C (68-79°F), a pH level of 6 to 8, and water that can be either soft or hard. For successful spawning, it's beneficial to have a densely planted aquarium. Plants provide hiding spots for the female and support for the male as he constructs his nest using mucous bubbles. Plants that reach the water’s surface are particularly helpful for nest construction.

Behavior

Paradise Fish, like many other anabantids, display notable territorial aggression, especially among males. While they are less combative than Siamese fighting fish, male Paradise Fish should be housed individually to avoid conflicts. If you must keep multiple males together, ensure the tank provides ample space for establishing separate territories and includes numerous hiding spots. In some cases, two males might even engage in homosexual behavior if kept in a large aquarium without any females present. Introducing a female often curbs this behavior. Paradise Fish should not be kept with slow-moving or long-finned fish, as they may be harassed or even eaten by the aggressive Paradise Fish. Females are generally less aggressive and can be introduced to males when they are ready to spawn. Observe the pair closely; if the male shows aggression, it could lead to injury or death for the female. To manage aggression, keep male Paradise Fish in separate tanks where they cannot see each other. If they can see their reflections or other males, they may display aggression by flaring their fins and gills, which can lead to chronic stress. To help manage their aggression, briefly place them in sight of each other or use a mirror to simulate the presence of another male, providing a form of controlled exercise.

Food

Paradise Fish are omnivores and thrive on a varied diet that includes both protein and vegetable matter. They eagerly consume mosquito larvae and ramshorn snails, but also require vegetables to maintain a balanced diet. Spirulina is an excellent addition, offering essential nutrients and enhancing the fish’s color. For a well-rounded diet, alternate between high-quality flake foods, live foods like brine shrimp or chopped earthworms, and algae wafers enriched with spirulina.

Sexing

Male Paradise Fish are more colorful and have longer, flowing fins compared to females. Their vibrant coloration and elongated, sometimes serrated, fin rays are used to attract females during the breeding season. In contrast, females are generally smaller, with shorter, rounder tails and fins lacking the extended rays. This distinction makes it relatively easy to identify males and females based on their physical characteristics.

Breeding

To encourage spawning, reduce water currents by turning off the filter or any equipment that creates turbulence. Feed both the male and female a high-protein diet of mosquito larvae, brine shrimp, or bloodworms to prepare them for breeding. The male will construct a bubble nest, usually under a broad leaf or piece of vegetation, using mucous-coated bubbles. Once the nest is ready, the male will court the female with elaborate displays. If she is not receptive, he may become aggressive. In such cases, provide her with hiding spots or temporarily remove her from the tank until she is ready. When she is ready to spawn, reintroduce her to the tank. The male will guide her to the nest, wrap around her, and help her release eggs. These buoyant eggs will float to the surface and be collected by the male in the nest. After spawning, remove the female to prevent aggression from the male. The male will guard the nest and care for the eggs until they hatch, which usually takes 24 to 48 hours. The fry will remain in the nest for a few more days until they absorb their yolk sacs.

Raising the Young

Once the eggs hatch, the fry will spend a few days absorbing their yolk sacs before needing external food. Initially, offer infusoria or finely crushed commercial fry food such as Hikari First Bites. After a week, introduce newly hatched brine shrimp and micro worms to their diet. Ensure the filtration system has minimal suction to avoid sucking up the tiny fry, or use a sponge filter to protect them. Providing hiding spots or moving them to a nursery tank can also safeguard them from predators and ensure a higher survival rate.

Sources

• Aquarium Fish by Ulrich Schliewen
• Encyclopedia of Aquarium and Pond Fish by David Alderton