International Journal of Aquaculture, 2026, Vol.16, No.3, 184-195 http://www.aquapublisher.com/index.php/ija 187 2.9 Statistical analysis Bacteriological characteristics and physiochemical analysis resulting from the experiment were subjected to one-way analysis of variance (ANOVA) using SPSS (Statistical Package for Social Sciences 2006 version 15.0). Duncan's multiple range test was used to compare differences among individual means. 3 Results 3.1 Water quality parameters of the experimental pond water The physicochemical properties of the experimental pond water showed a pH range of 7.0~8.5, Temperature 21.3 ℃ ~33.0 ℃, and Total suspended solids 25.0~41.0 (mg/L), and there were significant differences (p < 0.05) among the treatments in pH, temperature and total dissolved solids (Table 1). Table 1 Water quality parameters of the experimental pond water 1 0 2 4 6 8 Ph Pond 1 7.10±0.01a 8.00±0.06b 7.50±0.01ab 7.20±0.00a 8.50±0.06c Pond 2 7.40±0.03a 7.20±0.00a 8.00±0.04bc 7.50±0.04ab 7.50±0.04ab Pond 3 7.10±0.04a 7.50±0.01ab 8.50±0.03c 7.30±0.06b 8.00±0.02bc Pond 4 7.20±0.02a 7.70±0.03ab 7.70±0.02ab 8.50±0.08a 7.20±0.01a Pond 5 7.00±0.05a 8.20±0.05b 8.00±0.05bc 7.20±0.03ab 7.60±0.03ab Pond 6 7.30±0.07a 8.00±0.00b 7.20±0.02a 7.00±0.01ab 7.40±0.04ab Temperature (℃) Pond 1 21.30±0.02a 26.60±0.00c 27.90±0.03c 29.70±0.08e 33.00±0.09d Pond 2 25.60±0.08c 27.00±0.01c 25.00±0.02b 26.70±0.01c 27.30±0.02b Pond 3 23.70±0.04b 22.00±0.04a 21.60±0.01a 27.20±0.07c 25.20±0.03a Pond 4 30.40±0.09e 28.60±0.06e 22.70±0.95a 24.30±0.03a 29.00±0.07c Pond 5 28.50±0.06d 24.90±0.05b 31.20±0.09d 28.20±0.06d 25.00±0.05a Pond 6 25.80±0.07c 27.90±0.03d 22.00±0.06b 25.00±0.04b 27.00±0.03b Total dissolved solid (TDS) (mg/L) Pond 1 39.40±0.07e 29.20±0.03c 27.50±0.05b 36.50±0.02f 38.00±0.05c Pond 2 26.20±0.02b 25.50±0.00a 30.50±0.07d 31.60±0.04d 40.20±0.09d Pond 3 41.00±0.09e 36.20±0.05f 31.20 ±0.01e 29.60±0.06c 29.80± 0.01b Pond 4 30.20±0.08c 27.40±0.04b 28.50±0.02c 24.20±0.00a 30.00±0.03b Pond 5 25.00±0.05a 30.00±0.01d 25.60±0.04a 33.00±0.03e 27.50± 0.02a Pond 6 33.40±0.03d 31.00±0.2 e 30.00 ± 0.06d 26.20±0.01b 28.00± 0.04a Means (n =2) in the same column with similar superscripts are not significantly different (p > 0.05) 3.2 Bacteria counts of experimental pond water and fish tissues (gill, liver and intestine) A total of 30 water samples from the experimental fish ponds were analyzed for total bacteria counts at 0, 2, 4, 6 and 8th week and 54 fish tissues (gills, intestine, liver) from C. gariepinus juveniles in all the experimental ponds were analyzed for total bacteria counts at 0, 4 and 8th week. Test for the presence of presumptive P. shigelloides revealed that the bacterium was present in C. gariepinus tissues and experimental pond water. The Plesiomonas count on C. gariepinus tissues (gills, liver and intestine) ranges between 6.4 to 7.0 log10 CFU/g while the Plesiomonas count on experimental pond water ranges between 5.6 to 7.0 log10 CFU/mL. There was no significant difference (p > 0.05) in the total bacteria observed in the gill, liver and intestine and experimental pond water among the experimental groups except for experimental pond water at the 6th week who recorded significant differences (p < 0.05) among the groups (Table 2). 3.3 Isolation of Plesiomonas shigelloides A total of 250 isolates were obtained from both the aquaculture effluent (pond water) and fish tissues (gill, liver and intestine). Morphological identification was analyzed based on the shape, texture and colour of bacteria colonies on inositol brilliant bile green agar. The microscopic cell morphology analysis of the presumptive P.
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