5.0 DISCUSSION, CONCLUSION AND
bacterial load found in the skin, gill and intestine of Clarias gariepinus sampled from different farm locations in Ojo and
Badagry Local Governments of Lagos State was analysed in this study. The total
bacteria count, TBC (x 106CFU/mL) of the different parts ranged from
0.4 to 3.72. However, the result showed that the highest TBC was analyzed from
the intestine to be 3.72±0.81 and the lowest analyzed from the skin
(0.40±0.08). The result obtained in this study was similar in pattern to the
result observed by Abu and Uwadirioha (2016). The higher microbial load in the
gill and intestine of experimental fish may be due to increased bacteria that
were trapped in the gills and intestine during feeding and ingestion of food.
This was also observed by Akani and Obire (2014) in their study.
total bacterial count in this study was higher than the set standard for the
acceptable level of bacterial count/microbial safety of foods which is 1 to 100
cfu/mL (Ayinla et al., 1994). In
summary, the microbial load of the different parts of the experimental fish
collected from selected locations according to this study showed that fish
under culture is a reservoir of bacteria diversities. It is therefore noteworthy that
sanitary condition under which fishes are handled, fed and cultured be improved
upon to reflect standard or good management practices.
The biochemical characteristics of the isolated
organisms in the present study showed that there are both Gram positive and
Gram negative isolates, most of which are Gram negative. Most of the isolates are Bacillus (rod-like
shape) while only three (3) of the isolates are cocci (round shape). Most of
them are also motile while only two (2) are non-motile. Moreover, all the
isolates showed positive reaction to glucose fermentation and catalase tests.
They showed varied reactions to lactose, mannitol, maltose fermentation, urea
and oxidase tests. All the organisms are negative to indole test except one.
Also, the isolates showed varied reactions to methyl red, hydrogen sulphide (H2S)
and Voges proskaeur. Four isolates were negative and only one was positive to
coagulase test. Most of the organisms isolated were positive to sucrose
fermentation test and citrate reaction. Only one isolate was positive while
most were negative to indole reaction.
The result of biochemical characteristics identified
the presence of a total number of 16 bacteria species. Based on the analysis
done using standard microbiological methods, this study revealed the presence
aureus S. saprophyticus, Escherichia coli, Bacillus subtilis, B. mycoides, B.
megaterium, Micrococcus luteus, Proteus mirabilis, P. vulgaris, Pseudomonas
fluorescens, P. alcaligens, P. putida, P. aeruginosa, Aeromonas hydrophila,
Klebsiella specie and Citrobacter freudii, in
the gills, skins and intestines of the sampled fish.
occurrence of many Gram negative bacteria (E.
coli, Proteus mirabilis, Pseudomonas fluorescens, Aeromonas hydrophila, P. alcaligens, P. vulgaris, P. putida, Klebsiella spp., Citrobacter freudii and P. aeruginosa) and some Gram positive (Staphylococcus aureus, S. saprophyticus, Micrococcus luteus, Bacillus
subtilis, B. mycoides and B. megaterium) in the samples is in
concurrent with the work of Ibrahim and Adetuyi (2013). The isolation of Klebsiella spp, Proteus
spp. and E. coli from the fish
sampled indicated environmental contaminant and this supports the findings of
Yagoub and Ahmed (2004) and Naijah et al.
(2008). The occurrence of pathogenic bacteria especially E. coli in C. gariepinus may
jeopardize the fish health by causing infections in the fish under culture and
also induce diseases to human when in contact with them. Pseudomonas spp. and Proteus spp.
have been identified as responsible for some fatal diseases in fish as well as
zoonotic to man, Staphylococcus spp.
are known to cause severe diseases in man (Raghavan, 2003; Babu, 2000). Bacillus spp. and Staphylococcus spp. are major pathogens causing food borne diseases
(Bennett et al., 2013).
Although, pathogenicity of bacteria
isolates was not part of the focus, most of the bacteria species encountered in
this study are no doubt potentially pathogenic to different fish species under
culture especially Clarias gariepinus, as
also reported by Sowunmi et al (2008).
Length-weight relationship gives the
condition and growth patterns of fish. It provides important information
concerning the structure and function of fish populations (Hirpo, 2013). The
length and weight of experimental fish sampled from the different locations was
analysed. Result showed that the mean length (cm) ranged from 27.47±1.82 to
41.195±1.55 while the mean weight ranged from 155.26±25.44 to 483.62±41.21.
Length-weight relationship of the fish showed both linear and non-linear growth
pattern. However, the result showed that all the sampled fish had allometric