Improved health and better survival of farmed lumpfish (Cyclopterus lumpus) after a probiotic bath with two probiotic strains of Aliivibrio

Abstract

Cleaner wrasse eat sea lice (Lepeophtheirus salmonis) directly from the skin of the Atlantic salmon (Salmo salar). To reduce harvest from the wild wrasse populations and to increase the quality and availability of cleaner fish, lumpfish (Cyclopterus lumpus) have been increasingly developed as a service industry to the farming of Atlantic salmon in the last few years. Acquired resistance against the de-lousing chemicals is occuring at an increasing speed particularly in mid- and western-Norway has made the farming of lumpfish more important in the control of the sea lice infestations in farmed Atlantic salmon.Outbreaks of disease in farmed lumpfish occur in all its life stages. Some outbreaks of disease caused by pathogenic bacteria are resulting in high mortality while other bacteria cause lower but more chronic mortality. To reduce the mortality and improve the health of farmed lumpfish microbial enhancement with a probiotic bath approach has been tested.In five trials at two lumpfish aquaculture facilities in Norway, two probiotic isolates of Aliivibrio bacteria were added to the rearing water. The lumpfish were bathed in the probiotic bacteria in 10–30 min, the cfu (colony-forming units) of probiotic bacteria in the rearing water varied from 7.5 × 105 to 5 × 107/mL. The average weights of the lumpfish at time of bathing were from 0.025 g to 16.3 g in the various trials. The lumpfish were observed and sampled from 45 to 87 days after bathing. Growth, ulcers and survival were recorded.The survival of lumpfish in trials 3, 4 and 5 in which the fish were bathed 1 to 2 weeks before vaccination was significantly better for the probiotic exposed groups compared to the control groups. In trials 4 and 5, a natural outbreak of disease caused by Moritella viscosa occurred. The groups exposed to probiotic bacteria had significantly fewer ulcers than the control groups.The growth of the fish exposed to probiotic bacteria at weight 0.025 g was significantly better in the bathed group compared to the controls. In three trials the growth of the probiotic exposed lumpfish one to two weeks before vaccination was also higher than non-exposed fish.Bathing of lumpfish with two Aliivibrio bacteria increased growth and made the fish more resistant to bacterial diseases. To our knowledge, this is the first scientific report of probiotic bacteria applied to lumpfish.