Effect of probiotics on growth and microbiological changes in snakehead Channa striatus challenged by Aeromonas hydrophila

Abstract

The snakehead Channa striatus is widely preferred by consumers and is often affected by the
dreadful disease Epizootic Ulcerative Syndrome (EUS) and encounters losses in capture as well as
culture fisheries. Antibiotics, chemotherapeutants and vaccines are now commonly used in
aquaculture to prevent/treat fish diseases. Meanwhile an alternative safer way to tackle the disease
problem eco-friendly is to improve the resistance of target species by application of probiotics as
growth promoters and immunomodulators. The present investigation was attempted to find out the
effects of common probiotic strains Bacillus subtilis, Bacillus coagulans and Saccharomyces
cerevisiae and commercial probiotic Efinol®
FG on growth performance and microbiological changes
in normal striped murrel C. striatus and also those challenged by Aeromonas hydrophila. Probiotics
were added to the autoclaved semi moist feed and fed to the fingerlings. Feeding experiment was
conducted for 45 days. Growth measurements and total microbial count (TMC) were made once in 15
days for a total period of 45 days. Best SGR and FCR were estimated as a function of Efinol®
FG diet
and the difference in weight gain (16.37 g), SGR (4.22) and FCR (2.28) was found to be significantly
different (P<0.05) between Efinol®
FG diet and other probiotic diets. TMC is higher in Efinol®
FG fed
diet (7.7 × 10 8 CFU g-1
) than other fed diets. After that the fingerlings from each group were divided
into non-challenged (NC) and challenged by A. hydrophila by oral injection (OI) and intramuscular
injection (IM). Growth measurements and TMC were made again once in 7 days for a total period of
21 days. The challenged group of control diet (OI and IM) showed a drastic increase from day 1 (3.5 ×
108 CFU g-1
) to day 21 (7.1 × 10 9
- 8.8 × 10 9 CFU g-1
) whereas the OI and IM groups of all probiotic
diets showed a drastic decrease. In the case of OI group Efinol®
FG diet, the decrease was from 7.7
x108 CFU g-1
on day 1 to 2.0 × 10 8 CFU g-1
on day 21. The corresponding decrease in IM group was
from 7.7 × 1 08 CFU g-1
to 4.5 × 10 8 CFU g-1
. Regarding the equilibrium between competing beneficial
Efinol®
FG and pathogenic A. hydrophila, extension of experimental duration / increase in Efinol®
FG
concentration may help to arrive at a conclusion.