Effects Of Tank Cleaning Frequency And Sea Cucumber Co-Culture On Larval Sablefish Growth And Survival, Water Quality, And Microbial Communities

The larval period is the most labor-intensive and highest-mortality stage in marine fish aquaculture, due in part to the need to maintain good water quality. Organic matter from feed, fish waste, and algae (greenwater) can promote bacterial proliferation, including pathogens, and deteriorate water quality. Frequent cleaning methods are often employed to mitigate these effects, but cleaning is labor intensive and may have negative effects such as stress and physical damage to larvae, and disruption of potentially probiotic biofilm communities. In this study, we compared three tank cleaning methods: high cleaning frequency, low cleaning frequency, and low cleaning frequency with sea cucumbers (Parastichopus californicus). We assessed water quality, microbial community composition and abundance, and growth and survival of larval sablefish (Anoplopoma fimbria). Sea cucumbers have been shown to extract organic content in other aquaculture systems, but co-culture with sea cucumbers caused 98% larval mortality and is not recommended for sablefish larviculture. High and low cleaning frequencies did not differ in the types or numbers of bacteria present in tank seawater, or dissolved oxygen, ammonia, and nitrite levels. Further, high and low cleaning frequencies did not differ in larval sablefish growth or survival, indicating that low cleaning frequencies can be used to reduce labor costs without negative effects on larvae.