Many aspects of keeping and breeding of marine fish and invertebrates are still unknown. The aquarists have to watch their animals closely to recognize problems in husbandry and breeding to find solutions for these problems. For example, we observed that some coral reef fish larvae feed brine shrimp nauplia, but cannot digest them. Only unicellular marine zoo plankton is the correct food. This zooplankton again, feeds on marine phytoplankton. Therefore both plankton forms have to be cultured in a sufficient number. This can be only guaranteed, when we culture the zooplankton separately from the phytoplankton. We realized that zooplankton dies in water with higher salinity, whereas the phytoplankton is still growing very well. To make it easy to handle, we cultivated the phytoplankton with double salinity. When a special density of phytoplankton was reached, the salinity was reduced to normal and zooplankton added. Now you have to observe how many days it needs to reach such a high density of zooplankton that it can be used as food for the fish larvae. The number of days for the whole production reflects in the number of plankton tanks to make the production easy to handle.
Besides we realized that in black painted glass tanks it was not only easier to observe the tiny fish larvae, but also the tiny fish larvae hunted the zooplankton in front of the black wall more successfully so that the larvae grow quicker than in normal glass tanks.