Use of Different Biofilter Materials in Recirculating System of Nile Tilapia (Oreochromis niloticus)

Culture Chaibu1*, Chanagun Chitmanat2, Anupap  Wankanapol3 Numpet  Prakobsin4

1,2,3,4 Faculty of Fisheries Technology and Aquatic Resources. Maejo University. Chiang Mai, Thailand.
* Corresponding author :  e-mail: prachaub@mju.ac.th

Abstract
The purpose of this research was to determine the effect of different biofilter materials in recirculating system of Nile tilapia culture. Tilapia had cultured in 1 X 1 X 1.5 m.concrete recirculating ponds for three months. Four treatments with 3 replications each were carried out. Different filter materials were compared including; Treatment 1 Shading net filter materials; treatment 2 Coir filter materials; Treatment 3 vetiver fiber filter materials; and Treatment 4 nets filter materials. Nile tilapia were stocked at 100 fish/ m2, while 30 head lettuce per pond were planted. Average initial weights of fish in treatments 1, 2, 3 and 4 were 25.85±0.16, 25.98±0.27, 25.86±0.54, and 25.62±0.80 grams, respectively. By the end of experiment, the mean fish weight gains in treatments 1, 2, 3 and 4 were 97.72±0.40, 96.47±1.67, 96.05±1.24, and98.80±1.43grams, respectively. The tilapia in treatment 4 trended to provide the highest mean weight gain (73.18±1.77 grams), while tilapia in treatments 1, 2, and 3 had the mean weight gain as 71.87±0.48, 70.50±1.77 and 70.20±1.17, grams respectively. The mean length gains were 17.57±0.02, 17.53±0.03, 17.47±0.09, and 17.73±0.11centimeters, respectively. The average daily gains of tilapia were 0.80±0.01, 0.78±0.02, 0.78±0.01 and0.81±0.02, g/day, respectively. The highest survival rate was 94.33% found in treatment 4, while the fish survival rates in treatments 1, 2, and 3 were 94.00%, 93.67%, and 93.33%, respectively. Production of head lettuce at the end of experiment in treatments 1, 2, 3, and 4 were 414.04, 405.09, 409.29, and409.29grams, respectively. It was not significantly different (P>0.05) in the temperature, pH, ammonia, phosphorus, andturbidity among treatments. However, the value of DO was significant differences (P<0.05) ranging between 2.99– 3.13 mg/l. Nitrite in treatment 3 was significant differences (P0.05) with treatment 2. In conclusion, Shading net and nets were very effective to be used as filter materials for an recirculating system of Nile tilapia culture.

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