The Preliminary Study on the Potential of the Orange Halfbeak (Nomorhamphus ebrardtii) from the Sekoa River as an Exotic Ornamental Fish Commodity

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Abstract

The Sekoa River in Waole Village, Wolowa district, Buton island, Southeast Celebes, exhibits high ichthyofaunal diversity due to upstream freshwater springs and downstream marine influence. Initial fish sampling using a modified CPUE method revealed a community dominated by Gobiiformes (54%), Perciformes (20%), Beloniformes (10%), Carangiformes (4%), as well as Scorpaeniformes, Mugiliformes, Kurtiformes, and Anguilliformes (3% each). Notably, an endemic species, Nomorhamphus ebrardtii, was identified as a potential exotic ornamental fish. Subsequent research evaluated its adaptation under controlled aquaculture. Eighty N. ebrardtii individuals (0.60–0.80 g) were reared in ten 20-liter aquariums (34 × 40 × 37 cm) for 42 days. The study applied a Completely Randomized Design with three feeding rates of 1 mm commercial floating feed (5%, 10%, and 15% biomass) in triplicates. Parameters measured included absolute growth and length, survival rate, also water quality (temperature, pH, DO, ammonia, nitrate). ANOVA results indicated no significant differences among feeding rates. However, graphical trends showed the highest weight gain (0.144 g), and survival rate (53%) in the 15% treatment, while the 5% treatment achieved the maximum length gain (0.765 cm). The Sekoa River exhibits high ichthyofaunal diversity and harbors an endemic species, Nomorhamphus ebrardtii. The fish readily accepts commercial floating feed, with a 15% biomass feeding rate optimal for weight gain and a 5% rate for length increase. To ensure optimal survival and safety during rearing, a 15% biomass feeding rate is recommended. Additionally, attention should be paid if the fish display aggressive behavior, such as attacks on conspecifics or cannibalism, necessitating continuous monitoring or stocking density reduction if needed.