Spawning, Embryology, and Larval Development of the Milletseed Butterflyfish Chaetodon miliaris in the Laboratory

Abstract

As part of the Rising Tide Conservation effort to advance marine ornamental aquaculture the Milletseed Butterflyfish Chaetodon miliaris (also known as Millet Butterflyfish) was chosen as a candidate species for developing butterflyfish aquaculture methodologies. Thirty-five mature Milletseed Butterflyfish were imported to University of Florida’s Tropical Aquaculture Laboratory in Ruskin, Florida, from The Rainbow Reef exhibit at Aulani, a Disney Resort and Spa in Ko Olina, Hawaii, for evaluation. Spawning behavior was documented through personal and video observation five times. Eggs were collected immediately after spawning and checked for fertilization, and a sample of 100 ± 10 eggs were photographed every hour until hatching to document embryological development. Larval development was monitored through multiple rearing trials. Larvae were stocked into 128-L, cylindrical, rearing tanks at 15–20 larvae/L and fed nauplii of the copepod, Parvocalanus crassirostris, and the microalgae, Tisochrysis lutea, was added to green the water. Samples of larvae were measured using notochord length from the tip of the snout to the edge of the notochord prior to flexion, SL from the tip of the snout to the edge of the hypural plate, and TL. Spawning occurred in broodstock tanks between one dominant male and a single female with a large, swollen abdomen. Eggs of the Milletseed Butterflyfish were small, spherical, pelagic, and transparent and hatched after a 28-h period at 25.5°C. Newly hatched larvae had unpigmented eyes and a closed digestive tract and measured 1.20–1.24 mm in notochord length. Larvae were capable of feeding at 4 d posthatch (dph), fully absorbed the yolk sac by 7 dph, and began forming the tholichthys plates at 24 dph. Larvae survived to 44 dph in preliminary culture trials and measured 6.49–6.56 mm TL. Further investigation into the culture requirements of Milletseed Butterflyfish will supply a crucial base for developing aquaculture protocols for other marine ornamental species.

Received July 21, 2016; accepted February 17, 2017 Published online April 28, 2017

ACKNOWLEDGMENTS

The authors thank Judy St. Leger, Rising Tide Conservation Initiative, and Sea World and Busch Gardens Conservation Fund for funding and supporting this project. Thanks to the staff at Rainbow Reef exhibit at Aulani, a Disney Resort and Spa in Ko Olina, Hawaii, for supplying broodstock for this study. Thank you to Instant Ocean and United Pet Group for supplying marine grade aquarium salt and Piscine Energetics for helping supply food. Thanks to Larry Lawson, Amy Wood, Debbie Pouder, and Matt DiMaggio for their help and guidance in this study.