Parkinson's Rainbowfish

Parkinson's rainbowfish is easily told apart from other rainbowfish by the irregular orange-yellow blotches scattered especially over the rear half of its silvery-blue body. The shape and density of the blotches differ in every male; for this reason the individuals within a group do not look alike.

It is a large, calm species that reaches 11–12 cm. The colors become more distinct with age and during displays; young fish are silvery and plain. With its hardiness and wide water tolerance, it is a good choice for large community tanks.

It lives on the coastal plains at the southeastern tip of Papua New Guinea, in clear, planted streams, river branches and along swamp edges. The water is warm and soft to moderately hard; the fish gather in planted stretches where the current slows down.

• Volume: at least 200 liters and 120 cm in length for a school of 6–10.
• Water: 25–27°C, neutral to slightly alkaline, moderately hard water. 25–30% water changes every week.
• Decor: Dense plants and roots along the edges; plenty of swimming space at the front.
• Lighting: Good light and a dark substrate bring out the orange blotches.
• Lid: It jumps; the lid must fit tightly.

Omnivorous with a good appetite. Quality flakes and granules, frozen brine shrimp, mysis, bloodworms and daphnia; food with plant content several times a week. Foods containing carotenoids keep the orange blotches vivid. Feed small amounts 2–3 times a day.

Peaceful and somewhat calmer than its larger relatives. Males display to each other by spreading their fins; during this their colors darken noticeably. It eats fry and small shrimp and can frighten very small fish.

Good companions: large rainbowfish from other genera, Congo tetras, corydoras, bristlenose plecos, synodontis, botias, large rasboras.

Avoid: Neocaridina shrimp, aggressive cichlids, slow long-finned fish; if you plan to breed, other Melanotaenia species.

At least 6, ideally 10 or more individuals. A female-heavy group (2 females per male) is balanced; having more than one male increases display behavior and the intensity of the orange blotches. When kept in small numbers it stays shy and pale.

Like other Melanotaenia species, it is a continuous-spawning egg scatterer. In the morning hours a few eggs are laid every day on fine-leaved plants or a wool spawning mop. Move the eggs, which have sticky threads, to a separate container; the parents eat eggs and fry. The fry hatch in 7–12 days and are fed first infusoria and liquid fry food, then newly hatched brine shrimp. The males' blotches appear only after months.

Hybridization: It hybridizes easily with other Melanotaenia species; the blotches of hybrid offspring are faint or irregular. For a pure line, breed the species separately.

• White spot: can appear after a sudden temperature drop.
• Fading color: a sign of stress, a small group and poor water.
• Bloating: caused by overfeeding.
• In general it is hardy and long-lived.

Males are larger, with a deeper back, and carry orange-yellow blotches on the rear half; their fins are yellow-orange with dark edges. Females are smaller and slender, with a plain silvery-gray body and no orange blotches; their fins are colorless or slightly yellowish.