|Green, Bartholomew - Bart|
|Rawles, Steven - Steve|
|McEntire, Matthew - Matt|
Submitted to: Aquaculture America
Publication Type: Abstract Only
Publication Acceptance Date: 11/4/2019
Publication Date: 2/8/2020
Citation: Green, B.W., Schrader, K.K., Rawles, S.D., Webster, C.D., McEntire, M.E. 2020. Production of channel catfish using one-year-old or unused water in a biofloc technology production system [abstract]. Abstracts of Aquaculture America 2020, Honolulu, HI, 9-12 Feb 2020. p. 252.
Technical Abstract: Re-using water from an established mixotrophic biofloc technology production system over multiple production cycles would be beneficial because there would be no lag in the onset of biotransformation of excreted feed nitrogen. We conducted the present study in an outdoor biofloc technology production system stocked with channel catfish (Ictalurus punctatus) reared in one-year-old waters with low or high total suspended solids that was used previously for two consecutive biofloc experiments or in unused (new) water. Objectives of the study were to evaluate the impacts of the different waters on fish production characteristics and mineral status, common microbial off-flavors, and water quality dynamics. Tanks (18.6 m2, 15.7 m3) were stocked with fingerlings (47.5 +/- 0.8 g/fish) at 13.5 fish/m2 (16 fish/m3) and grown for 181 days. Total suspended solids were maintained at 300 to 400 mg/L in the unused and low total suspended solids used water treatments and allowed to accumulate in the high total suspended solids used water treatment. Water type did not affect significantly any channel catfish production characteristic. Gross fish yield averaged 10.2 kg/m3, fish averaged 642 g/fish, FCR averaged 1.36, and survival averaged 99.6%. Nitrate accumulation rate was affected by total suspended solids concentration with a significant reduction observed at the highest discharge of solids from the system, suggesting wash-out of nitrifiers. Treatment effects on water quality dynamics, macro- and trace-mineral status of water, feed, and fish, 2-methylisoborneol and geosmin off-flavors and associated phytoplankton populations also are discussed. Results of this study suggest that one-year-old biofloc water can be used without adverse impact for a second year of channel catfish production in the biofloc system.