FISHERIES RESEARCH INSTITUTE,MOA,TAIWAN

In this study, experiments were conducted to investigate the half lethal temperature, suitable feeding temperature, and effects of different temperatures and diets on the growth of swamp eel (Anguilla marmorata) elvers. Swamp eel elvers were reared for one day at 25 °C, then cultivated further as the water temperature was increased or decreased continuously at the rate of 1 ℃ per hour. As the water temperature rose to 36.6 °C, the elvers started to die, and when it had reached 38.2 °C, all the elvers had died. When the water temperature declined to 8.3 °C, a few elvers died, while all the rest had died by the time it reached 6.8 °C. The upper and lower lethal temperatures were estimated to be 37.1 °C and 7.6 °C, respectively. In another experiment, after elvers were stocked at 25 °C for one day, the water temperature was increased or decreased for 1 °C per day. The elvers had the highest feeding rate at 29.2 °C. At over 30.2 °C, their feeding rate slowed down, and at 37.0 °C, it had completely stopped. In the growth trial, 300 swamp eel elvers were reared in four thermo-regulated recirculating tanks at 15, 20, 25, and 30 °C for 6 weeks. The elvers reared at 30 °C had the best growth rate (713.3%). That growth rate was not significantly different from that of the elvers reared at 25 °C, but it was significantly higher than the rates for those reared at 20 °C and 15 °C. The feed conversion ratio of the elvers reared at 25 °C was better than those of the elvers reared at 30, 20, and 15 °C. A 30-day experiment was also conducted on four kinds of diets for swamp eels. The group cultivated with a living wiggler diet attained the highest percent weight gain (820.2%), which was significantly higher than those of the groups reared, respectively, with paste feed, a frozen wiggler mixed eel diet, and an eel diet. In conclusion, tropical swamp eel elvers can be cultivated successfully indoors when reared in controlled water temperatures in the range of 25~30 °C and fed with paste feed.