Chilatherina fasciata [Lake Wanam] - photo© Neil Armstrong

Chilatherina fasciata

Species Summary
As with many rainbowfishes, Chilatherina fasciata often display a great variation in body colour and markings depending on location. Throughout New Guinea there are effective natural barriers that isolated various populations, thus contributing to the number of different colour variations. Generally, they have a body colour of brown to bluish-green on the upper half, white to yellowish on the lower half with a diffuse dark mid-lateral stripe. Scales of this region often bordered with pale yellow. Males usually have several diffuse blackish bars on the lower sides, above the front half of the anal-fin base; fins dusky grey to yellowish. Males are generally deeper bodied than females, this feature becoming more obvious with increased growth. In addition, the posterior profile of the dorsal and anal fins is more pointed and elongated in males. In contrast to males, which have longer posterior dorsal rays, females have the longest rays at the anterior part of the fin. Finally, mature males are more colourful than females often exhibiting reddish or yellowish dorsal and anal fins. While spawning the males colour becomes very intense and the top of the head radiates a brilliant bronze to vermilion hue. Females are basically silver to olive overall with clear fins. Perhaps the most distinguishing feature of Chilatherina fasciata is their deep, laterally compressed body that increases with age, particularly in males. Males may reach a maximum size of 12 cm, but females are usually less than 10 cm. Diet includes filamentous algae, small crustaceans, terrestrial insects (particularly ants and tiny beetles), and aquatic insect larvae.

Chilatherina fasciata [Clearwater Creek] - photo© Neil Armstrong

Distribution & Habitat
Chilatherina fasciata is probably one of the most abundant and widely distributed rainbowfishes in northern New Guinea. They have been found in tributaries of the Markham, Ramu, Sepik, Neumeyer and Mamberamo River systems of northern New Guinea. They have also been collected from Lake Wanam, near Lae in Papua New Guinea.

Chilatherina fasciata have been collected mainly in clear, slow-flowing rainforest streams, generally inhabiting deeper pools that are exposed to sunlight for most of the day. These streams usually have a substrate consisting mainly of gravel or sand and littered with leaves and other debris. The natural pH and temperature ranges have been reported as 6.2~ 8.1 and 27~32° Celsius.

Remarks
Dr. P. N. Van Kampen first collected Chilatherina fasciata in June 1910 in a stream near Njao, West Papua. Live specimens were collected for the aquarium hobby by Barry Crockford and Gerald Allen during several trips to Papua New Guinea in the late 1970's and early 1980's. Around 1983, live specimens were also collected from the Jafuri River, an outlet of Lake Sentani which flows into the Pacific Ocean near the Papua New Guinea border.

Heiko Bleher has collected live specimens for the aquarium trade from various locations in New Guinea. The latest colour variant was collect in 1999 from Lake Nenggwambu or Kali Biru Lake in West Papua. He collected only males and had to return a second time in order to collect females. This variety has a broad orange stripe from the tip of its snout to the first dorsal fin. There is a vigorously flowing outlet stream, but no apparent inlet, indicative of a subterranean connection with neighbouring lakes via the limestone substratum. Water was relatively clear and maximum depth was estimated to be at least 10~15 m. The lake is surrounded by secondary forest and aquatic plants were abundant, but relatively few species were evident. Fishes were most strongly congregated around the outlet, where vegetation was very dense. Glossolepis dorityi was also collected from this location.

Chilatherina fasciata [Mamberambo River] - photo© Neil Armstrong

Literature
Allen, G.R. (1991). Field guide to the freshwater fishes of New Guinea. Christensen Research Institute, Madang, Papua New Guinea.

Weber, M. (1913). Süsswasserfische aus Niederländisch Süd- und Nord-Neu-Guinea. In: Nova Guinea. Résultats de l'expédition scientifique Néerlandaise à la Nouvelle-Guinée. Zoologie. Leiden. Zool. Nouvelle-Guinée 9(4): 513-613.

© Copyright Adrian R. Tappin
Updated December, 2008.