Working with Milletseed Butterfly’s (Chaetodon miliaris) has presented some unique challenges. After experiencing some issues during shipping and quarantine, we made some changes, and have a batch of 23 healthy, vibrant fish from Disney’s Rainbow reef, in Hawaii. The fish are eating very well and spawned twice during quarantine. However, due to the chemicals in the water during quarantine, the eggs were not viable. This gives us hope that we will soon have viable eggs to start working with since the fish are out of quarantine and the water free from chemicals. Eggs are approximately 710 microns in diameter, with a central oil globule. Fertilized eggs will float on the waters surface and are skimmed off the surface with egg collectors in the tank.
Non viable eggs of milletseed butterfly’s collected in the quarantine tank
We canulated the broodstock in an effort to determine what sex ratio and stage of maturity was present in our population. The results were quite shocking. Out of 19 fish that were cannulated only 1 was male. Shouldn’t he be in heaven! Having already spawned we do not think that this will be a major issue, however it may limit fecundity of the group. Our goal is to gather several more males and introduce them to the population.
Oocyte samples taken by canulation of female milletseed butterfly’s. Left shows primary growth oocyts. Right shows mature oocytes.
Tropical Aquaculture Laboratory | University of Florida