Influence of Heterotrophic Feeding on the Survival and Tissue Growth Rates of Galaxea Fascicularis (octocorralia: Occulinidae) in Aquaria

The propagation and growth of scleractinian corals under aquaculture conditions could reduce the pressure of extractive fishing for ornamental species. To fulfil their growth requirements, corals rely on a combination of photosynthetic products translocated from symbiotic zooxanthellae, and particulate heterotrophic sources. In aquaculture, the latter is provided by Artemia sp. nauplii as they provide adequate nutrition and promote optimal growth and survival. In this study, we evaluated feeding rates and estimated growth rates of cultured scleractinian corals. Polyp and colonial nubbins of the coral Galaxea fascicularis were randomly assigned to each of three tanks within three naturally lit systems under standard conditions. Corals were subjected to three feeding treatments: i) fed once or ii) three times weekly, or iii) unfed until the end of the trial (two months). The survival rates were 98.7% and 100% for the colonial and polyp forms, respectively. Ingestion rates of Artemia salina nauplii between the three feeding treatments were significantly higher for specimens fed 3-times a week compared to those two treatments involving a lower feeding frequency (individual prey items polyp−1 20min−1: 8 vs. ≤ 4, respectively), but growth rates of colonial and polyp forms were not significantly different with respect to feeding frequency. Mean rate of new polyp growth was ca. 4 polyps nubbin−1 week−1 for colonial form and ca. 1 polyp polyp−1 week−1 for the polyp form. The high survival and growth rates of G. fascicularis, coupled with an apparent low heterotrophic prey requirement, make this species an ideal candidate for commercial propagation in aquaculture.