Female biology and early life aspects of the swamp eel (Monopterus albus)
Thumronk Amornsakun, Ponpanom Promkaew, and Anuar bin Hassan
DOI: 10.14456/sjst-psu.2018.173
pp. 1420 - 1427
Abstract
The sexual maturity of the female swamp eel (Monopterus albus) was studied by determining its fecundity and
gonadosomatic index (GSI). The body weight of a sexually mature female swamp eel was 200-250 g. The eggs were nonadhesive demersal and rounded. The maximum fecundity was in June at 701 ova/fish with a gonadosomatic index (GSI) of
3.09%. The minimum recorded fecundity was 181 ova/fish in October with a GSI of 0.57 %. The average diameter of the eggs
was 1,784 µm. The fish eggs were classified by diameter into seven groups: 250-750 µm (12.25%) as group 1, 751-1,250 µm
(15.62%) as group 2, 1,251-1,750 µm (14.76%) as group 3, 1,751-2,250 µm (31.50%) as group 4, 2,251-2,750 µm (18.87%) as
group 5, 2,751-3,250 µm (6%) as group 6, and 3,251-3,750 µm (1%) as group 7. Newly hatched larvae of the swamp eel were
produced by the semi-control natural method. Newly hatched larvae had a mean (SD) total length (TL) of 1.76±0.06 cm with a
mean (SD) yolk sac volume of 1,279.14±101.50 μm3
. The yolk sacs were completely absorbed within 174 hours after hatching
(hAH) at a water temperature of 28,0-30.5 °C. All larvae were able to open their mouths at 108 hAH (2.50±0.17 mm TL), with a
mean (SD) height measurement of 785.00±30.83 μm. The digestive tract was straight, and was placed on the yolk sac. The
digestive tracts were formed at 116 hAH with a mean (SD) length of 845.00±30.75 μm. The average number of Moina sp. in the
digestive tract at the start of feeding was 0.83 individuals/larva. The larvae died within 1,092 hAH at water temperatures that
ranged 27.0-30.5 °C. It was found that the feeding scheme of the larval swamp eel was as follows: larvae of age 5-15 days (total
length 2.81-3.30 cm) consumed Moina sp., but at age 12-15 days (average total length 3.2-3.30 cm) the larvae consumed both
Moina sp. and a commercial pellet known as ‘power feed’. Larvae more than 16 days old (average total length 3.20 mm)
consumed only ‘power feed’.
