International Journal of Aquaculture, 2018, Vol.8, No.14, 104-111
105
Pesticides at high concentrations are known to reduce the survival, growth and reproduction of fish (Rathore
and Nollet, 2012). Due to the residual effects of pesticides, important organs like gonads, kidney, liver, gills,
stomach, brain and muscle are damaged. In Bangladesh, more than 300 types of insectides and pesticides are used
for crop protection in agriculture. Over 98% of sprayed insecticides and 95% of herbicides reach a destination
other than their target species, including non target species, air, water, bottom sediments, and food (Miller and
Miller, 2004).
Chlorpyrifos (IUPAC name:
O
,
O
-diethyl
O
-3,5,6-trichloropyridin-2yl phosphorothioate) is a crystalline
organophosphate insecticide, acaracide and miticide (Figure 1). It was introduced in 1965 by Dow Chemical
Company and is known by many trade names including Dursban and Lorsban. It acts on the nervous system of
insects by inhibiting acetylcholinesterase.
Chlorpyrifos is moderately toxic to humans, and exposure has been linked to neurological effects, persistent
developmental disorders and autoimmune disorders. According to Dow, chlorpyrifos is registered for use in nearly
100 countries and is annually applied to approximately 8.5 million acres. The crops with the most use are cotton,
corn, almonds and fruit trees including oranges, bananas and apples. In agriculture, chlorpyrifos is commonly
used as a foliar spray, or applied directly to soil and incorporated into it before planting. Exposure to sub-lethal
concentrations of chlorpyrifos has caused the severe effects in species of freshwater and marine fauna: ataxia,
delayed maturation, growth and reproduction impairment, deformities and depressed populations (Marshall and
Roberts, 1978).
Trichogaster fasciata
, the stripped gourami, is a tropical labyrinth fish native to Bangladesh (Figure 2). It is
bentho pelagic and prefers weedy environments such as ponds, large rivers, ditches, lakes and rice fields. Size of a
fully grown male can be up to 12 centimeters (4.7 inches). Females are usually a little smaller and are used for
food in its natural habitat. The natural resources of this species are declining fast, especially in Bangladesh, due to
drastic reduction of its natural feeding and breeding ground as a result of human intervention, climate change and
habitats modification. At present,
T. fasciata
under ‘lower risk near threatened’ as least concern category although
is not listed in the IUCN Red Data Book 2015. To date, so far no study has been carried out describing the
potential toxic effects of chlorpyrifos on the reproduction of striped gourami. Therefore, the present study was
conducted to evaluate the physiological toxicity of striped gourami induced by chlorpyrifos through the
histopathological alterations of gills.
Figure 1 Chemical structure of Chlorpyrifos 20 EC
Figure 2 The stripped gourami
Trichogaster fasciata
The major objectives of the present research work was to investigate the effect of chloropyrifos on the
histo-architecture of gills of stripped gourami as well as to find out the histopathological responses of the gills in
stripped gourami exposed to various concentrations of chlorpyrifos. Further, the potential health risks to consumer
due to the intake of this chloropyrifos contaminated fishes.
