Bacteriological study of shrimp, Penaeus monodon Fabricius, hatcheries in India
Shrimp hatcheries often face problems of mortality
caused by diseases. To understand the bacteriological status of shrimp, Penaeus
monodon Fabricius, hatcheries in India, a study of hatchery water at
different points was conducted in several hatcheries located along the east
and west coast of India. The species composition of the bacterial flora was
also determined. The total plate counts of raw sea water on tryptic soya
agar ranged from 102 to 104 ml-1,
whereas it ranged from 104 to 106 ml-1
in larval tanks. In the larval tanks, the proportion of Vibrio
species ranged from 50% to 73%, as compared to 31% in raw sea water. A mixed
bacterial flora was observed in hatchery water; however, in the larval
tanks, the flora in the larvae was predominantly made up of Vibrio
species. A few of the tested Vibrio isolates were non-virulent to
shrimp larvae under experimental conditions. Over 90% of the strains were
resistant to amoxycillin, ampicillin, cephalexin, cephazolin, cloxacillin
and sulphafurazole. Most strains showed sensitivity to tetracycline,
chloramphenicol, and quinolones such as norfloxacin and ciprofloxacin.
(Department of Fishery Microbiology, College of
Fisheries, Mangalore – 575002, India. E-mail of I. Karunasagar: mircen@giasbg01.vsnl.net.in)