Aquaculture Department, Faculty of Fisheries and Marine Sciences, Diponegoro University, Semarang, Indonesia
Aquaculture and Fisheries Group, Wageningen University, Wageningen, The Netherlands
The sustainability of prawn farming in brackish water ponds is controversial because of low yields and mangrove clearing. Low yields are due mostly to insufficient preparation of pond bottoms. Mangrove trees are often planted on pond bunds as window dressing. This study examined the effect of three types of liquid compost from vegetables, fruit, and both vegetables and fruit in tanks to which whole or chopped Avicenia marina leaves were added to mimic local pond conditions. In a split-plot design, 28 square tanks were each stocked with one hundred 15-day-old post-larvae tiger prawns (Penaeus monodon). Four tanks were used as controls and 24 were assigned to the treatments, 12 with whole and 12 with chopped leaves. In both of these 12, 4 received liquid compost from vegetables, 4 from fruits and 4 from their mixture. Shrimp were weighed at the start, halfway and end of the 50-day trial, and fed at 5% of the estimated total weight; survival was counted at the end. The survival rates of treatments and controls (65–76%) were not significantly different. Shrimp in water with vegetable compost grew significantly faster (2.7% day−1) than in both treatments with fruit (2.5% day−1). Shrimp in all treatments grew significantly faster than those in the controls (2.0% day−1). The lower growth rate of shrimp fed fruit compost may have been due to dinoflagellates, which are known to negatively affect shrimp. Shrimp in tanks with chopped leaves of A. marina grew slightly better than shrimp in tanks with whole leaves.