Effect of different amounts of green mussel shell ( Perna viridis ) on the reproductive and spawning rate of the endemic Ajamaru Lake rainbowfish ( Melanotaenia ajamaruensis Allen & Cross, 1980)

Ajamaru Rainbowfish ( Melanotaenia ajamaruensis ) is an endemic species of Lake Ajamaru, Papua, Indonesia, and inhabits water at a pH of 6.5 – 8.5. However, the reproductive rate of the Ajamaru rainbowfish and what factors influence it are not widely known. This study aimed to determine the reproductive capacity of the Ajamaru Rainbowfish. A pair of male and female fish with a ratio of 1:1 were used during the study. The pH of the water was increased by adding different amounts of Perna viridis green mussel shells. The dosages used for the treatments were 0, 2, 4, 6, and 8 g/l, with three replications for 30 days in the Jakarta Technical University of Fisheries Laboratory. Fish spawned naturally every two days for 30 days. Fish fed blood worms 5% of their weight. The parameters observed were the calcium content of mussel shells and water media, water quality (pH, alkalinity, temperature, and oxygen), spawning frequency, number of eggs, fertilization rate, and hatching rate. The results showed that 2 g/l green mussel shells gave the highest value at 15 spawning times, fertilization rate/FR was 97.16%, hatching rate/HR (%) was 97.93, and 537.67 ± 89.37 larvae. Increase in pH 7.42-7.7 from 6.45-6.47.