Breeding Arowana

Breeding Arowana

The Silver Arowana prefers a 125 gallon tank with a fine gravel bottom, loosely planted, and soft, peaty water with lots of open space above for swimming. The aquarium must be fitted with a tight, heavy cover because the Arowana will jump, particularly when after prey. After breeding, the male Silver Arowana is responsible for carrying the large eggs in his mouth where they mature in 50 to 60 days. When young, these fish are easily harassed by more aggressive species such as Cichlids, Knife fish, large Plecostomus, Catfish, and Ornate Bichirs make good tank mates for the Silver Arowana. A carnivore, the Silver Arowana will eat other smaller fish, water fleas, mosquito larvae, as well as freeze-dried ocean plankton, krill and pellet foods.

HABITAT: Bangladesh.

Spawning behavior

The fish shows unique courtship behavior. The courting chase takes place from several days to weeks before the pair starts to mate. They will swim in circles with male chasing the female.

About 1-2 weeks before spawning takes place, the fish swims side by side and perform body contact between pair. After the courtship behavior takes place, the female will lay the eggs and then promptly fertilized by the male. After fertilization, the male picks up the eggs and incubates them until the fry can swim and survive independently.

The eggs are large in size about 8-10mm and yolk rich, hatched about one week after fertilization. After hatching, the young larvae continue to live in the male’s mouth for further 7-8 weeks until the yolk sac was totally absorbed. The size of the fry was 45-50mm before they are move out of the males’ buccal cavity.

REMOVING OF EGGS FROM MALE'S MOUTH

In the study, the fertilized eggs were forced extruded from males’ mouth at the 30th day after spawning. The average number of the eggs produced in a single brood was 21 larvae with the maximum number recorded 29.

The eggs are orange-red in color and are large in size with diameter 16-20 mm. Once removed from the parents’ mouth, the half-developed larvae were incubated in glass aquarium tanks, measuring 90x45x45cm. Water temperature is kept around 27-29 degree C using a thermostat heater and dissolved oxygen is maintained at about 5 ppm (mg/l) through continuous aeration of the water. During the first few weeks when the larvae are still having large yolk sac, they tend to remain at the bottom of the tank most of the time. The fry start to swim upward periodically when the yolk sac becomes smaller.

Using the in vitro hatching technique, the survival rate to free swimming stage achieved is 90-100%. The fry will swim freely on the 7th week. Supplementary external live feed (young guppy) was given at the early free-swimming stage to avoid the fry from attacking each other. At the age of the 6th month the fingerlings were reared individually in 75 x 45 x 45cm re-circulating water system tank. At this age the fry measured about 20-25cm length and were ready for market.

Eight pieces of Malaysian Golden Dragon were reared in 5m x 5m concrete tank and water depth about 0.5m. pH of water was maintained between 6.8-7.5 and temperature 27-29oC. A ’spawning room’ were built at one corner of the concrete tank. It is hoped that the condition will create a natural living environment for the fish. Live feed such as crickets, wild guppy, freshwater prawn (Macrobrachium lanchestrii) and gold fish were given daily. Pellet feed was also given as the supplementary food.

MATURITY

The fish attain first maturity from the 4th year onwards and measure between 45-60cm. The fish spawn throughout the year with the peak season occurring between July and December. In nature the male incubates the fertilized eggs in its’ bucca cavity until the fry is free swimming at about 2 months.

Sexual differences are indiscernible in juvenile stage and become apparent after maturity is reached in about 3-4 years. Male posses slimmer and shallower body depth, bigger mouth and more intense color then the females.

The reasons for having wider mouth and deeper lower jaw in males are for eggs incubating purposes. The size of the males’ head is relatively bigger. Male is more aggressive and leading in competition for food.

A brooding male can be recognized by its remarkable brood pouch underside its mouth.