EFFECT OF STOCKING DENSITY ON GROWTH, SURVIVAL AND PRODUCTION OF THAI KOI (Anabas testudineus) FRY IN THE NURSERY PONDS OF NILPHAMARI DISTRICT OF BANGLADESH

Abstract

The present study was carried out to assess the effect of stocking density on the growth, survival and production of Thai koi (Anabas testudineus) in the farmer‟s seasonal nursery ponds of Nilphamari district for a period of 30 days. There were three treatments each having three replications. Around 0.2g weight of Thai koi were stocked at the rate of 1200, 1400 and 1600 fry per decimal in T1, T2 and T3 respectively. All the experimental fish were fed with a commercial feed containing 35.53% crude protein (nursery Lily fish feed) three times daily at a rate of 25% body weight for the first 10 days, 15% for the second 10 days, and finally 10% for the last 10 days. During the experimental period the water quality parameters were suitable for fish culture. The water temperatures were ranged from 27.20 to 27.6 ; transparency 26.98 to 33.50 cm, pH 6.34 to 8.70, dissolved oxygen 5.02 to 5.17 mgL-1 ; and total alkalinity 99.40 to 109.10 mgL-1 . Significantly higher (P<0.05) transparency, NH3, alkalinity and hardness were observed in the higher stocking density compared to those treatments where the stocking density were lower. The weight gain (6.35±0.90g), specific growth rate (SGR 11.26±0.41 % per day) and protein efficiency ratio (PER 4.59±0.71) were significantly increased (P<0.05) after 30 days feeding trial in the treatment T1 compared with the other treatment groups. While, a significantly lowest (P<0.05) feed conversion ratio (FCR) was observed in the treatment T1 followed by T2 and T3. Significantly the highest (P<0.05) survival and production were observed in the treatment T1 compared with the remaining two treatments. At the end of the experiment the benefit-cost ratio (BCR) revealed that best BCR was 2.04 in T1 which did not differed significantly (P>0.05) when compared with T2. Therefore, the results of this study indicated that the lowest stocking density (1200 fry dec-1 ) seems to have a more positive influence on the enhancement of the growth performance and feed utilization of Thai koi (A. testudineus) fry in the seasonal farmer‟s nursery pond.