High dose propofol effectively euthanizes zebrafish (Danio rerio)

Abstract

We evaluated propofol overdose for euthanasia of zebrafish (Danio rerio). We hypothesized that 1) propofol 40
mg/L at 10 min submersion euthanizes zebrafish as effective as 20 or 30 min submersion; 2) propofol 80 mg/L at 10
min submersion euthanizes zebrafish as effective as with 100 or 120 mg/L. Wild-type AB zebrafish were randomly
submersed into: Exp.1 - propofol 40 mg/L for 10, 20, or 30 mins; or Exp.2 - 80, 100, or 120 mg/L for 10 mins. Criteria
monitored: aversive behavior; time to loss of righting reflex (LORR); undulation cessation; operculation cessation; fish
movement from tank tap reflex cessation; and euthanasia rate. Results: No aversive behavior noted; LORR 5 sec for
both experiments; undulation cessation: 22 sec (Exp.1), 5 sec (Exp.2); operculation cessation: 66 sec (Exp.1), 51 sec
(Exp.2); fish movement from tank tap reflex cessation: 13 min in the 20 and 30 min groups, and fish still moved in the
10 min group (Exp.1), no fish movement in any groups (Exp.2); euthanasia rate: 30% in 10 min group and 100% in 20
and 30 min group (Exp.1); 90% in 80 mg/L group, 50% in 100 mg/L group and 100% in 120 mg/L group (Exp.2).
Propofol 40 mg/L at 10 min submersion does not euthanize zebrafish as effective as 20 or 30 min submersion; 2)
propofol 80 or 100 mg/L at 10 min submersion does not euthanize zebrafish as effective as 120 mg/L. Propofol at 40
mg/L for at least 20 min or 120 mg/L for 10 min submersion effectively euthanizes zebrafish.