Response and recovery of hybrid sturgeon from subchronic oral administration of cyanobacteria

A 90-day growth trial was conducted on hybrid sturgeon (Acipenser baeri ♀ × A. gueldenstaedtii ♂) to investigate the effect of dietary inclusion of cyanobacteria on growth, feed utilization, and fish tissue microcystins (MCs) accumulation and the recovery of fish when they were free of cyanobacteria. Four diets were formualted isonitrogenous and isocaloric to contain different MCs concentrations: the control diet (free of cyanobacteria), low cyanobacteria diet (LCD, 26.60 μg MCs/g diet), medium cyanobacteria diet (MCD, 78.82 μg MCs/g diet), and high cyanobacteria diet (HCD, 201.03 μg MCs/g diet). During the first 47 days, each diet was fed to fish in five replicates and then all fish were fed the control diet during the next 43 days. The results showed that a dose-dependent decrease in feeding rate (FR) and specific growth rate (SGR) were observed in the fish fed with MCD and HCD. MCs contents in fish liver, intestine, and dorsal white muscle increased with dietary MCs and were time dependent (P < 0.05). After the 43-day recovery, there were no significant differences in FR or SGR between the fish previously fed LCD or MCD and the fish fed with the control diet (P > 0.05), while the fish previously fed HCD showed higher FR and SGR than those fed the control diet (P < 0.05). MCs clearance in fish liver and intestine showed time-dependence during the 43-day recovery.