Analysis of plankton intake to the growth and omega-3 fatty acid content of milkfish (Chanos chanos forsskal, 1775)

The aim of the present study was to examine the food, growth, and omega 3 fatty acid content of milkfish (Chanos chanos) in Sidoarjo fish pond, East Java. The study was conducted by spreading 5,000 fish milkfish seeds (5-7 cm long and 0.6-1.0 g) to the fish pond. The length and weight of milkfish were measured, and the digestive tract was isolated. For sampling, a plankton net was used and samples were preserved in 1% Lugol solution. Data were analyzed to determine the food type and selection, growth rate, relative intestine length, and weight length relationship. The recorded relative intestine length of milkfish was 5.4-6.4 cm and was categorized as herbivorous fish. The food type was phytoplankton with a length of <14 cm and zooplankton with a length of >15 cm. The proportion of zooplankton in the fish intestine increased with its size. The phytoplanktons found dominantly in the digestive tract were Chaetoceros sp. and Nitzschia sp. and zooplankton were Calanus sp. and Cyclop sp. The daily length growth rate ranged from 0.008 to 0.283 cm, while the daily weight growth rate ranged from 0.5 to 1.16 g. The length-weight relationship of milkfish (Chanos chanos) can be determined by equation W=0.1466x with the regression index R2=1. Thus, milkfish (Chanos chanos) tended to have isometric growth patterns with the length and weight and were directly proportional to the omega-3 content in the milkfish body.