Survival of Goldfish and Golden Shiner in Different pH

Goldfish Carassius auratus and golden shiner Notemigonus crysoleucas are two major baitfish species cultured in Arkansas. These fish species are sensitive to pH and related water quality stress in ponds. Fish farmers in Arkansas usually report fish ‘disappearance’ in baitfish ponds. pH could be one possible cause for the ‘disappearance’. The current experiments were conducted in 4-liter plastic transparent aquaria (each aquarium was filled with 3-liter de-chlorinated tap water) in the laboratory, early June 2010. A total of two 24-hour pH toxicity tests were conducted for goldfish (3 days posthatch and n = 20 per aquarium, initial pH = 8.83, 11 triplicate pH treatments ranging from pH = 3.57 ± 0.08 to pH =11.56 ± 0.09) and golden shiner (30 days posthatch and n = 20 per aquarium, initial pH = 8.46, 10 triplicate pH treatments ranging from pH = 3.56 ± 0.24 to pH =11.48 ± 0.13), respectively. The experimental aquaria were aerated continuously during the experimental period. Fish mortality was observed after the 24-hour pH exposure.

Dissolved oxygen (DO) and temperature were relatively stable during the experimental period for both tests. For the 3 days posthatch goldfish, the 24-hour LC10s of pH (i.e., pH with 10% of mortality) were 9.01 and 6.23, respectively. And the 24-hour LC50s of pH (i.e., pH with 50% of mortality) were 10.57 and 4.66, respectively. For the 30 days posthatch golden shiner, the 24-hour LC10s of pH were 9.36 and 5.36, respectively. And the 24-hour LC50s of pH were 10.70 and 4.02, respectively. These two fishes were generally more sensitive to increased pH than decreased pH at the current initial pH values. The 3 days goldfish were more sensitive to pH change than the 30 days golden shiner.