Isok barb
(Probarbus jullieni)

Identification

This fish has many identifying characteristics. Most noticeable are its five longitudinal stripes above its lateral line. For its teeth, it has large pharyngeal teeth in a single row. Pharyngeal teeth are located in the throat of some species of fish, specifically the pharyngeal arch of these fishes’ throats. In order to feel, it has maxillary barbels-whisker-like appendages that serve as tactile organs near its mouth. These whiskers allow it to better feel its surroundings. For movement, it has a dorsal fin with one spine and nine branched rays, and five branched anal rays. Its maximum total length is approximately 165 cm and its maximum weight is approximately 70 kg. It can live up to 50 years and gradually grows in size over time. This is responsible for its large size.

Behavior

This fish eats freshwater shellfish, prawns, and aquatic plants. They tend to eat more during the wet season, when food is abundant, and less during the dry season when food is scarce. Like many other river fish, its lifecycle is dependent on monsoon rains, which means that the Jullien\'s golden carp occupies different regions throughout the year depending on the season.

Reproduction

This fish is migratory, and its migratory pattern centers around its mating season. Adults migrate upstream during the dry season to form spawning communities in deep pools of low water. Once the spawning is over, the recently hatched fish enter floodplains during the rainy season. This means that its migratory pattern centers around the shift from dry to the rainy season. This migratory pattern is vital for the survival of this endangered species, but various threats to its habitat, such as aquaculture and hydropower development threaten this pattern, and thus their existence.

Habitat

Historically, this fish was found in the Mekong, Irrawaddy, Chao Phraya, Meklong, Pahang, and Perak River Basins of Southeast Asia, specifically in Thailand, Laos, Cambodia, Vietnam, Myanmar, and Malaysia. Now, this fish is found mainly in the Mekong River Basin, however there are some small populations in the Phahang and Perak River Basins. In these river basins, Jullien\'s carp are found in fast rapids and clear pools of water. During the rainy season they live in deep waters, but during the dry season, which is also their spawning season, they live in shallow waters.