3.2. Modified ‘planktonkreisel’ (MPK) design
The MPK has similar functionality and ease of use along side the 3-L and 9-L tank designs. Interestingly, the MPK design has a distribution of circular flow velocities, with flow being more gentle towards the middle and top of the tank and faster along the curved floor, which fish larvae appear to respond to. During pilot studies, larvae were often observed to position themselves in the tanks in an area of preferred water velocity, which was generally away from
the faster flow on the tank floors. The MPK has potential as a tool to rear more challenging, sensitive marine ornamental larvae beyond early larval stages, up to settlement and post larval ages. In particular, recent pilot studies supported growth and development of C. cyanea to flexion and presettlement ages (Table 1 ), which has previously only been achieved in larger tank designs (Gopakumar et al., 2009). This design has also been successfully used for in situ observation oflarval feeding in M. atrodorsalis and S. splendidus (Table 1 ), allowing for side-on viewing of larval swimming and feeding patterns, without the need to move the larvae to observation tanks. In a similar manner to the 3-L and 9-L designs, the MPK design has been used with a simple water bath recirculating system, and uses less live feeds and algae than larger tanks, when employing the conventional green water culture method.