Blue Mahseer – Neolissochilus stracheyi – Thai Fish Species

Species: Neolissochilus stracheyi.

Common name: Stracheyi Mahseer, Blue Mahseer. Thai Name: Pla Puang.

Distribution: Found in Asia from Myanmar through the Southeast Thailand river systems.

Habitat: Blue Mahseer are commonly found in freshwater rivers and streams with fast-flowing and clear and well-oxygenated water. They are known for their powerful swimming abilities and can navigate through strong currents. They prefer habitats with rocky or gravelly bottoms and a good amount of aquatic vegetation, close to rapids. Which afford the shy and elusive Mahseer plenty of cover. These rivers are typically located in hilly or mountainous regions. Blue Mahseer can also inhabit lakes and reservoirs, especially if these water bodies are situated in hilly or mountainous areas. In such environments, they prefer areas with submerged rocks and ample cover. Often associated with aquatic vegetation, as it provides shelter and serves as a source of food.

It’s important to note that Blue Mahseer populations have been declining due to various factors, including habitat degradation, and water pollution, overfishing, and dam construction, which can disrupt their natural habitat and migration patterns. Conservation efforts are being made in many regions to protect and restore their habitats and populations.

Blue MahseerBlue Mahseer (Neolissochilus stracheyi)

Is a freshwater fish species in the Cyprinidae family of the order Cypriniformes (Carp). They have a streamlined compact body which is typical of most Mahseer species adapted for swimming in fast flowing rivers. They have large scales in a golden or coppery hue on their upper body, which gives them a distinct appearance. Along their sides, there is a prominent and dark lateral line. This line is a sensory organ that helps the fish detect vibrations and changes in water pressure, assisting them in navigating turbulent waters. The lower part of their body (belly) is typically silver or white.

The name “Blue Mahseer” is derived from the distinct bluish coloration on their dorsal fin, anal fin and caudal fin, as well the pectoral and pelvic fins. Together with the colors of the body, gives them an incredibly beautiful appearance. They have a fleshy, protrusible mouth with thick lips. Small barbels, which are fleshy, whisker-like, that help them locate food in murky waters. They have relatively large eyes, which helps them navigate and hunt prey in fast-moving water.

It’s important to note that in appearance Blue Mahseer can vary somewhat based on their age, habitat, and environmental conditions. They change color according to the surroundings, in bright surroundings they will often be in golden/coppery color, and they can be very dark if the surroundings have shade.

Lifespan and Size

The lifespan of Blue Mahseer can vary depending on various factors, including their habitat, water quality, and availability of food. In general, Blue Mahseer have a relatively long lifespan compared to many other freshwater fish species. They can live for 15 to 25 years in the wild under suitable conditions. In the first year of life the fry typically grows to about 3-4 inches (7.5-10 cm) in length, if provided with suitable conditions.

After the first year, the growth rate may slow down, and the fish may grow around 1-2 inches (2.5-5 cm) per year, depending on environmental factors. Factors like water temperature, diet, and water quality can significantly influence their growth rate. The species can reach a maximum size of around 7 kilograms (15 lbs.) with a length of around 70 cm. The present world record is 4.5 kilograms (9 lbs. 14 oz) Caught in the waters of Nam Song River, Laos, on November 29, 2011.


Blue Mahseer are omnivorous fish, meaning they consume both plant and animal matter in their diet. Their diet in the wild typically consists of a variety of food sources found in their natural habitat. While animal protein is an important part of their diet, they do consume aquatic vegetation and algae to some extent. As well detritus, which is decaying organic matter found at the bottom of rivers and streams. They also feed on insects and aquatic invertebrates such as aquatic insect larvae, small crustaceans, worms and small fish, particularly fish fry and smaller species that they can capture in their habitat. These protein-rich sources are an essential part of their diet.

Blue Mahseer Breeding Timeline

They reach maturity at a size of 12-18 inch. (30-45 cm) or more, which can take several years, depending on the conditions. Blue Mahseer are known to spawn during the monsoon season when water levels rise, and conditions become more favorable for reproduction. Blue Mahseer undertake upstream migration, moving to specific spawning grounds. These spawning grounds are often in areas with clear water and suitable substrates for egg attachment, such as gravel or rocky areas. They are known as egg scatterers, the female releases her eggs into the water, and the male releases sperm to fertilize the eggs. This process usually occurs in areas with moderate to strong water flow, ensuring that the fertilized eggs are carried downstream.

The fertilized eggs are carried by the current until they settle on suitable substrates. Blue Mahseer eggs are adhesive, allowing them to stick to rocks or gravel, where they remain until they hatch. The incubation period for the eggs can vary depending on water temperature and other factors. Once the eggs hatch, the fry is left to fend for themselves in the wild. They rely on natural food sources in the river or stream. Many predators, including other fish species and aquatic insects, may prey on the eggs and fry. Survival rates can be relatively low, and only a portion of the hatched fry will reach maturity.


Gender determination of Blue Mahseer can be challenging, especially when they are juveniles or not in breeding condition. However, there are some physical and behavioral differences that can help distinguish between males and females as they reach maturity. In general, female Blue Mahseer tend to be slightly larger than the male, although this size difference may not be very pronounced. Mature females may exhibit a more robust or muscular appearance.

In the breeding season, males will often develop more vibrant and intense colors, particularly on their fins. Males will also become more territorial and aggressive as they compete for the attention of females. The males may display courtship behaviors to attract females, such as chasing, circling, and displaying their vibrant colors.

Blue Mahseer Fishing method

Fishing for Blue Mahseer can be an exciting and challenging endeavor, as these fish are known for their strength and fighting ability. The angler will need to venture to some of the densest jungles and remote locations. In search of one of this most prized of freshwater fishes. The specific fishing methods used for Blue Mahseer can vary depending on the location and the angler’s preferences.

Lure fishing with medium to heavy spinning rods and reels is a popular method for catching Blue Mahseer. Use a variety of lures, such as artificial baits that mimic species that the Mahseer prey on can be effective. Vary your retrieve speed and depth to find the most productive presentation. Cast your lure into areas such as deep pools, eddies, or behind rocks. Bait fishing can be effective, especially in areas where live bait is permitted. Common baits include live or dead fish, worms, crickets, or other natural baits.

Fly fishing can be a rewarding experience for anglers who enjoy using fly tackle. Use, streamer-type flies or dry-flies that mimic fish or insects that Blue Mahseer prey on. Our experience is that fly fishing is the most productive way in the rivers. Because by using this technique, it is easier to present the bait without spooking the fish.

Consider practicing catch and release to help conserve the populations, especially in areas where they are threatened or protected. Handle the fish gently, avoid removing them from the water for extended periods, and use barbless hooks to minimize injury.

Source: Wikipedia Fishbase

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