International Journal of Aquaculture, 2018, Vol.8, No.11, 77-89
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With these qualities,
Clarias
could help to alleviate the problem of inadequate supply of animal protein in Nigeria
if both the cultured and feral stocks are properly managed. Such management aspects include its protection from
anthropogenic toxic substances introduced into aquatic environments. Most of these substances are deliberately
added to water, though not aiming at killing fish. Fish become the victims as Olufayo (2009) and Gupta and Singh
(2011) pointed that they are the most sensitive to pollutants.
One such pollutant is 2, 4-Dimethyl Amine, an herbicide introduced into aquatic environment to control weeds in
rice farms. Knowing well that rice and fish are environmentally related, for they both have affinity for riparian
environment (Ada et al., 2013). Therefore, chemicals used in weed control in rice farms may not only annihilate
weed plants but also non-target organisms. It is observed to cause neurotoxicity, reproductive and developmental
toxicities (U.S. EPA, 2005). It interferes with cellular metabolism by disrupting acetyl-coenzyme A (CoA) and
uncoupling of oxidative phosphorylation due to either the disrupted CoA activity or cellular membrane damage
(Akobundu, 1987; Hussein et al., 1996). In plants, it is a secondary plant growth regulator and is used to
selectively kill plants. It kills plants by causing their mitotic cells to divide uncontrollably. According to NPIC
(2011) ‘abnormal increase in cell wall plasticity, biosynthesis of protein and production of ethylene occur in plant
tissues following exposure resulting in uncontrolled cell division’. The herbicide which is a salt, dissociates to
acid form in water (NPSC, 2011) As Deshmukh (2016) pointed out, blood parameters in fish are influenced by
many factors such as temperature, salinity, oxygen, hydrogen ion concentration of the water which affects the
respiratory metabolism. The influence of agrochemical on fish blood has been intensively investigated by
scientists. These include the works of Ayoola and Ajani (2008) that investigated the histopathological Effects of
Cypermethrin on juvenile African cat fish; Cengiz et al. (2001) investigated the Histopathological Effects of
Thiodin on the liver and gut of mosquito fish,
Gambusia afini
; Gabriel et al. (2007) studied the haematology and
gill Pathology of
Clarias gariepinus
exposed to refined Petroleum oil, Kerosene under laboratory conditions;
Agbon et al. (2002) carried out acute toxicity of Diazonon to Rotifers, Cyclops, Mosquito larvae and fish;
Kori-Siakpere et al. (2007) studied acute Haematological effects of Sub lethal levels of Paraquat on the African
Catfish. Though Dimethyl amine is more frequently used in aquatic environment, more work on its effects has
been carried out in terrestrial organisms than in aquatic organisms. It is shown not to be very toxic to rat with the
LD
50
values: 736 mg/kg (mouse, i.p.); 316 mg/kg (mouse, p.o.); 698 mg/kg (rat, p.o.); 3900 mg/kg (rat, dermal);
240 mg/kg (guinea pig or rabbit, p.o.) (NIEHS, 2008).
This work was therefore carried out to determine the lethal concentration of 2, 4-Dimethyl Amine and to observe
the haematologicel changes that occur in
Clarias gariepinus
during exposure. Assessment of the influence of
2, 4-Dimethyl Amine on the water quality parameters as well as measurement of the effects of 2, 4-Dimethyl
Amine on the condition factor, gonadosomatic and hepatosomatic indices were carried out
.
1 Materials and Methods
The study was carried out in the wet Laboratory of the Department of Fisheries and Aquatic Science, Cross River
University of Technology, Obubra Campus. 600 apparently healthy looking fish were obtained from Institute of
Oceanography, University of Calabar. The fish were batch weighed using a digital scale (Model EK-5350 made by
BIBBY scientific Ltd, UK) and acclimated, prior to the experiment, in a plastic holding tank. These fish weighed
906.7±39.3 mg and length 164.7±10.2 mm (Gabriel et al., 2007). During this period, the fish were fed 5% of their
total body weight, with 2 mm COPPENS industrial feed. The rations were divided into two parts, and feeding was
done at 9:00 am and 5:00 pm daily (Olatayo, 2004). Thirty liters of stream water was measured into each transparent
plastic aquarium of lengths, widths and heights of 52 cm, 38 cm and 30 cm, respectively (Ada et al., 2016).
1.1 Toxicity experiment
A total number of 10 fish was randomly selected and stocked in each aquarium (APHA, 1981; Cengiz et al., 2001;
Olatayo, 2004; Ayoola and Ajani, 2008; Ayotunde et al., 2015; Ada et al., 2017). A static bioassay method was
used in this experiment. There was no replacement of the stock solution throughout the experiment. There was no
aeration of water during the range finding test.
