Evaluation of the Ciliated Protozoa, Fabrea salina as a First Food for Larval Red Snapper, Lutjanus campechanus in a Large Scale Rearing Experiment

Abstract

ABSTRACT One of the major challenges of culturing of red snapper, Lutjanus campechanus, is providing an appropriate food source at onset of feeding. Ciliates are abundant in marine waters but their significance as a first food for fish larvae is poorly understood as many have no lorica to facilitate their identification in the gut of a larval fish. Fabrea salina is a naked heterotrich ciliate that can be mass cultured at densities up to 84 ± 10 ciliates/mL in 7 days. Its appropriateness as a first food for red snapper larvae was evaluated in a green-water setting using 1-m3 tanks. Larvae were stocked at 10/L, 36 h post-hatch, before first-feeding commenced. Larvae were fed either (1) copepod nauplii, 20–75 μm, only from days 1 to 10; (2) copepod nauplii from days 1 to 10 plus F. salina from days 1 to 5; or, (3) F. salina only from days 1 to 3 plus copepod nauplii from days 4 to 10. Copepod nauplii were added at 2/mL and ciliates were added at 5/mL. Survival after 28 days was 0.28 ± 0.15% for larvae given only copepod nauplii and 2.39 ± 2.75% for those given F. salina and copepod nauplii. Larvae given only F. salina did not survive past 4 days post-stocking. Larvae were more actively feeding in the tanks given F. salina and copepods as first foods with 34.6 ± 8.5% mean daily reduction in copepod nauplii compared to 15.8 ± 16.2% reduction when only nauplii were provided.