Keralites are familiar with spotted butterfish, which is locally known as ‘Nachara’ or ‘Kachayi’, as an edible fish available in the coastal area. But it has a high demand as an ornamental fish in global level. Spotted butterfish is also called spotted scat or scat. Its scientific name is Scatophagus argus.
The fish is commonly found in the prawn farms and brackish water. A two-inch long spotted butterfish costs Rs 30-35 in local market whereas it fetches Rs 100-120 in the international market. The fish grows upto 40 cm in natural conditions.
Spotted butterfish is flat shaped towards its sides and has a rather small head. Its fins are similar to hand fans. The greenish black spots all over the body is the notable feature of the fish. Its body is normally found in green, greenish grey or greenish brown colour.
Spotted butterfish lives in groups. So, it is ideal to keep more than one fish in the aquarium. Since they swim a lot, large aquarium tanks are good for growing spotted butterfish. The fish is likely to die in case of high nitrate presence, so that use filters in the tanks.
If they are gradually familiarised, spotted butterfish grows in freshwater also. The smaller fish can survive the changes in the salinity of water, but the larger ones seem to die. Ideal pH level of water is between 7.5-8.5.
The Central Institute of Brackishwater Aquaculture in Chennai has developed a technology to produce seeds of spotted butterfish artificially. Fish that weighs 200 gram can be chosen for reproduction.
The fish will be ready for laying eggs within 48 hours of injecting hormones. Normally, stripping (obtaining eggs from female fish) is required for reproduction. The eggs will hatch within 18-20 hours of fertilisation.
Spotted butterfish are omnivores. They feed on algae, worms, mosquito larvae and even artificial fish food. The fishlings are fed with rotifers soon after they are hatched, and artemia larvae after they turn 10 days old. When they grow up to 7-9 mm (about 25 days old), they can be fed with artificial feed.