FROM GENERATION TO GENERATION: CULTURING ZEBRAFISH UNDER CONTINUOUS ILLUMINATION FROM FERTILIZATION TO ADULTHOOD

The popularity of zebrafish in multiple disciplines has caused a surge of research on zebrafish larviculture, growth, and reproduction, to optimize biological characteristics of this model species. While many studies investigating growth, survival and generation time of zebrafish have been conducted, investigation into the effect that continuous illumination has on these factors has been scarce. Furthermore, the investigation of the effects of constant light on zebrafish over multiple generations has yet to be conducted entirely. Thus, this study examined growth, survival, and generation time of zebrafish raised under continuous illumination in a novel experimental system from the time of fertilization to adulthood over 6 generations, F1-6.

Larviculture methods utilized in this generational study were based on initial investigation of zebrafish culture under continuous illumination (Dabrowski and Miller, in prep.). Zebrafish larvae, across all generations, were stocked to the experimental system at 5 dpf (days post- fertilization) and fed live saltwater rotifers, Brachionus plicatilis. At 12 dpf, larvae were transitioned to live Artemia nauplii for the duration of the experiment.  Individuals were measured throughout the experiment, no significant differences in weight or length at 21 dpf were observed between F1-6 (Figure 1). Once fish reached size where males and females could be differentiated, spawning pairs were set each 24 h period (subjected to 10 h dark) until spawning and fertilization were successful.  Generation time was determined as the number of days post fertilization when spawning was first successful (Table 1). Successfully spawned males and females were measured after each spawning, size at sexual maturity, and no significant differences in weight or length between F1-6 were observed (Figure 2).  

The study is ongoing and data for F7-9 will also be presented. Results suggest that zebrafish can be successfully grown under continuous illumination, and that doing so produces a higher growth rate and shorter generation time than the suggested 10 h dark, 14 h light regime (Lawrence 2007).  Based on the presented results, 8 generations of zebrafish can be produced in 1 year following this methodology, reducing the time required for multigenerational selection, a trait useful in various research fields.