Submitted to: Aquaculture America Conference
Publication Type: Abstract Only
Publication Acceptance Date: December 1, 2007
Publication Date: February 9, 2008
Citation: Ott, B.D., Torrans, E.L. 2008. Routine Metabolic Rate of Channel Catfish Ictalurus punctatus Fry [Abstract]. In: Book of Abstracts. Aquaculture America. February 9-12, 2008, Lake Buena Vista, Florida. p. 273. Technical Abstract: Channel catfish eggs are typically incubated at high density and are often subjected to sub-optimum dissolved oxygen (DO) concentrations while in the hatchery. Since DO plays an important role in the development, hatch rate, and growth of catfish eggs and fry, we measured routine metabolic rate of channel catfish fry to better understand hatchery DO requirements as catfish fry develop. Metabolism measurements were taken in a closed respirometer consisting of a 300mL Wheaton BOD bottle fitted with a Hach BOD overflow funnel. Oxygen consumption and temperature were measured using a Hach model HQ10 luminescent dissolved oxygen meter equipped with a magnetic spin bar on the tip of the probe. Spawns (n= 6-7) were either collected from ponds or produced by strip-spawning at the Thad Cochran National Warmwater Aquaculture Center, Stoneville, MS. Catfish fry metabolism was initially measured 6 hours post-hatching (hph) and every day thereafter up to 35 days post hatch (dph). For each measurement, a fry sample was collected in a dip net, patted dry and weighed (0.55-2.40g), and placed in the respirometer where DO and temperature measurements were taken every minute for 30 minutes at an average water temperature of 26.7 ± 0.04°C. The fry were then removed and individually counted (n= 18-273) to determine average weight. Oxygen consumption rate was lowest (0.008 ± 0.001 mg O2• individual-1•h-1) when first measured at 6 hph and increased roughly linearly throughout the study period. At swim-up (5 dph), oxygen consumption rate had increased 3.2-fold, and by 9 dph, oxygen consumption rate had increased 4.5-fold from initial measurements. Due to limited space, water and/or aeration capacity, most farmers are unable to meet this oxygen demand and must move the fry out of the hatchery a few days after swim-up. If farmers could increase the oxygen supply to meet the fry metabolic requirements for an additional growth period in the hatchery, fry survival in the pond would likely increase.