The golden domino damselfish (Dascyllus auripinnis) is an ornamental fish native to the Indo-Pacific and highly sought after by aquarium hobbyists. Closely related to the three-spot damselfish (Dascyllus trimaculatus), the appearance of the golden domino damselfish differs with a distinct golden underbelly. Development of early culture protocols for this species contributed to successful culture of juveniles through metamorphosis at 42 days post hatch (DPH) at the University of Florida. With an extended larval period and heavy reliance on live feeds, such as rotifers (Brachionus spp.) and Artemia spp. nauplii, the transition to an inert diet would help reduce reliance on costly live feeds and simplify larval rearing to facilitate future commercial culture of this species. However, inert diets often contain more complex macromolecules that are difficult to digest compared to the free amino acids and highly unsaturated fatty acids (HUFAs) found in live feeds. To ensure proper weaning of larvae from live feeds to inert microdiets, the maturation of the larval digestive tract should be understood to select appropriate weaning timepoints, which can be species specific. This study sought to characterize the digestive physiology of D. auripinnis to inform timing for introduction of microdiets and reductions in live feed consumption.
Larval digestive physiology of D. auripinnis was examined from 3 – 30 DPH, where larvae were sampled at six time points throughout development. Digestive tract maturation will be indicated by the formation of a functional stomach, which will be determined through histology and digestive enzyme quantification. Histology will verify the onset of intestinal coiling and activation of gastric glands in the stomach via periodic acid-Schiff staining. Additionally, the activity of digestive enzymes such as pepsin, trypsin, and lipase will also be measured via standard microplate assays characterize the ontogeny of these enzymes. Results of these analyses will determine when D. auripinnis larvae can digest a more complex diet, ultimately reducing live feeds, and providing insights into the development of other closely related species.