Often reefs are torn up to get at those fish that are out of reach. By controlling water temperature and light, Holt can recreate in the lab conditions that are ideal for spawning. But once the fish spawn, providing food for the fish larvae poses another challenge. For the first few days of life, fish require a diet of live food that is tiny enough for the almost microscopic size to eat. Along with Nancy Marcus, a researcher at Florida State University, Holt identified copepods as a food that might keep the young fish alive.
Copepods are tiny crustaceans that spend a large portion of their lives as inactive eggs.
Holt has successfully bred and raised several species of ornamental shrimp, such as this peppermint shrimp. Marcus devised a way to produce copepod eggs in the lab and she determined the conditions needed to make them hatch, releasing larvae that serve as food for the tropical fish larvae. Marcus then shipped copepod eggs to Holt, who induced hatching and fed the copepods to young tropical fish. Holt found that some tropical fish larvae that were fed copepods have a 23 percent greater survival rate and grew much faster than those fed other foods. Currently, Holt is working with several species of coral reef fish and ornamental shrimp.