NATURAL BREEDING OF CHOCOLATE GOURAMY (Sphearichthys osphromenoides)
UNDER ARTIFICIAL CONDITION

 Mohamad-Zaini, S., Saadon, K. &  Mansor, A.2001
Freshwater Fisheries Research Centre
Batu Berendam, 75350 Melaka,
Malaysia

Introduction

The blackwater of the Malayan forest area has a very rich biodiversity of fish fauna. There are 47 species fish found from a blackwater site in North Selangor Peat Swamp Forest. Among the blackwater fish species collected, 27 were recognized as already or having very good potential to be exploited for aquarium industry (Peter et al, 1992). The species appeared to be confined to the highly acidic, dark-colored water known as stenotopic acid blackwater species. They thrive and breed well in such habitat. Studies have been done to establish commercial breeding technique for the potentially good blackwater fish for aquarium trade. One of the stenotopic acid blackwater species is the Chocolate Gouramy (Sphearichthys osphromenoides) known to be a highly priced and popular aquarium fish. The chocolate gouramy belongs to the group of anabantidae. It possess labyrinth, a special respiratory organ enables the fish to breathe atmospheric oxygen. Unlike others Anabantoids the Chocolate Gouramy is a mouth brooder.

Collecting The Wild Fish

Traditional hand-scoop for catching wild fish

Collecting specimens from natural habitat

The specimens of wild Chocolate Gouramy are collected from peat soil area by scoop-netting the sluggish and stagnant dark-brown peat water ditches among palm and coconut plantation off Air Hitam, Muar, Johor. The fish thrives very well in the brown, soft, highly acidic water pH around 5.0-6.0 and rich in humic acid but very low dissolved oxygen content. It can easily found under rotting plant material in the peat water area.

Wild-caught of chocolate gouramy

Chocolate gouramy is very peaceful and can be kept with other fishes. But it is advisable to keep the fish among themselves because of their timid behavior. The fish can be kept in aquarium without aeration. The newly caught wild fish are quite susceptible to fungal infection and need to be placed in quarantine tank for at least 2 weeks. Prophylaxis treatment using a mild concentration of methylene blue (fungi inhibitor) should be carried out for preventive measures especially when the fish suffer injuries during catching or handling. The quarantine period can be extended between 25-30 days to ensure wild-caught specimens are fully recovered and acclimatized in aquarium environment. Since the wild fish refuses to accept formulated feed, live food such as bloodworm, tubifex worm, mosquito larvae or Moina should be given. During the period of acclimatization the fish should be monitored frequently to observe the behaviors and feeding habits. Normally after 2 months most of the fish are well adapted and acclimatized in tank condition as seen their tendency to approach us without fear during feeding.

The domesticated chocolate gouramy are reared in an aquarium tank measuring 30x30x30cm with the volume of water about 20-25L. The pH of water should be adjusted to about 6.0-6.5 with the hardness <50ppm and the iron Fe²⁺<0.5ppm. A piece of driftwood is placed in the aquarium for the fish to hide. The water should be filtered mechanically using a corner filter through acrylic wool and activated charcoal. To prepare a tannin-stained dark brown water, 100g of sphagnum peat moss is soaked in 30L of water. After 5-7 days the domestic tap water will turn to artificial black water with the pH around 5-6. To enhance the dark color of the water and increase the tannic effect of the water, 10-15 pieces of dry leaves of Sea Almond (Ketapang leave) are soaked in the water. Rearing tank should be placed away from any disturbances. 

Brooding female

For breeding purposes the adult Chocolate Gouramy should be fed with live foods such as Moina sp., Daphnia sp. or mosquito larvae. To stimulate the natural environment the rearing tanks are provided with an artificial living condition by placing some pieces of bogwoods and floating water plants. After about 2 months of pre-conditioning the fish succeeded to breed naturally in these tanks.
Sex differences are difficult to distinguish. Normally the size of male is greater than female. Its’ anal fin deeper and more pointed in male whereas it is blunt in female. The prime female can easily be recognized by its’ plump-belly. The male attract the female by spreading its’ fin and chasing each other in a circle. Chocolate gouramy, unlike other anabantoids which are bubble nest builder, it is a prolific mouth brooder. During spawning mood the females’ throat pouch turn to reddish color and the color of male body becomes dark chocolate. The male chases the female in a circular motion. Spawning usually takes place in an isolated place or secluded from other fishes. Female lays eggs on the bottom of the aquarium and the male fertilized the cream colored eggs. The eggs size is fairly large in size, approximately 1.8-2.0 mm. About 60-70 eggs are released per spawning. After the spawning has completed the female starts to collect the fertilized eggs and keep them in its mouth pouch. During incubating period female doesn’t take any external food. The free-swimming fry usually emerge from the mothers’ mouth in about 14 –15 days after spawning.

Newly-released fry

The free-swimming fry should be transferred to another rearing tank measuring 30x30x30cm with the volume of water about 20L. The size of newly released fry ranged from 0.4-0.5 cm in length. The daily feeding with Artemia nauplii enhances the fry to grow very quickly. Tank reared fry can attained the length of 2.6cm and weight of about 2.5g in two months. The fry can be marketed at the age of 3 months when the length is 3.0-3.5 cm. The average percentage of survival is 50% and the maximum percentage of survival is 74%.

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