Improved protocol for rapid zebrafish growth without reducing reproductive performance

Despite widespread use of zebrafish Danio rerio (Hamilton) as a model organism for finfish aquaculture, genetics and molecular biology, husbandry methods and nutrition have not been standardised. We characterise a protocol for rearing zebrafish using a recently developed combination of environmental parameters that yield rapid growth rates: high densities of live food organisms (marine rotifers and brine shrimp nauplii), low salinity, continuous light and algal turbidity during larval and early juvenile stages (5-21 days post fertilisation, dpf) followed by a transition to conventional rearing methods (dark/light photoperiod, freshwater). We assessed a range of larval fish densities in a stagnant water system with continuous ad libitum feeding until 21 dpf and periodic water changes. Fish stocking densities of 12-22 fish/L gave maximum growth rate and growth rate declined as stocking density increased past this threshold. Survival rates during 5-21 and 21-42 dpf were 87 +/- 9 and 98 +/- 3% respectively. Mean +/- SD weight and length were 64 +/- 9 mg and 19.4 +/- 1.0 mm at 21 dpf and 245 +/- 28 mg and 30.4 +/- 1.5 mm at 42 dpf. Fertility was assessed at 66 +/- 3 dpf. Mean clutch size was 232 +/- 124 oocytes/female and fertilisation rate was 72 +/- 16%. This protocol will significantly increase productivity in zebrafish facilities.