Clownfish are the most ubiquitous marine aquarium aquaculture species. Despite the success of the clownfish aquaculture, there is still a need to improve larva l rearing methods due to the high variability of hatch, survival, and deformity rates. One way to improve these parameters is by disinfecting embryos just prior to hatching . D isinfecting embryos can reduce or eliminate bacteria, fungi, or protozoans from being transferred to the larval system. Common disinfection treatments include hydrogen peroxide, iodine, and formalin. This study aims to determine effective concentrations needed to disinfect embryos and spawning substrates.
Three disinfectants were tested at various concentrations on common clownfish (Amphiprion ocellaris) embryos . Range finding experiments evaluated p ovidone iodine (1 00 ppm, 250 ppm, and 500 ppm), h ydrogen p eroxide (1,000 ppm, 5,000 ppm, and 10,000 ppm), and formalin (10 ppm, 10 0 ppm, 200 ppm), a long with a seawater control for each treatment . A. ocellaris breeding pairs were conditioned to spawn on acetyl sheets. One day before hatching (8-9 days), the acetyl sheet w as removed from the tank , and the sheet was cut into four equal groups of embryos . Each sheet was exposed to various disinfectant concentrations for 5 minutes. After 5 minutes, embryos were transferred into clean seawater and reaffixed to a ceramic tile for hatching. The tile was placed in 20 L of seawater in a custom 3-D printed hatching apparatus that orients the tile at a 60-degree angle and holds a wooden air diffuser to aerate the embryos (Figure 1). The embryos were held in complete darkness to hatch overnight. The next morning, numbers of unhatched embryos , living hatched larvae, and dead hatched larvae were enumerated to determine the percent hatch and percent survival.
Determining effective embryo disinfection methods improves larval rearing efficiency by helping to reduce harmful microbial communities and increase hatch rate. In turn, this will help to reduce economic losses in research and production facilities rearing clownfish .