Abstract
The comparative studies on the biology and culture of the freshwater mud eel (Monopterus
cuchia) and the freshwater spiny eel (Mastacembelus armatus) of Mymensingh region
have been carried out during May 2000 to November 2002 in the Department of
Aquaculture, Faculty of Fisheries, Bangladesh Agricultural University, Mymensingh.
Morphometric and meristic counts of 261 and 217 specimens respectively were made for
males and females of both the species separately. An application of 'Z' test showed no
significant difference between the male and female of the eel species. The values of lengthweight regression for males and females for both the eel species were practically identical
and very close to the ideal 3. The Kn values were determined for males and females of the
both species separately, according to size and month. The relation between the total length
and weight of male, female and sexes combined of the mud eel and the spiny eel were
found satisfactory. The haematological parameters of both the species like total erythrocyte
count, haemoglobin concentration, haematocrit values and neutrophils count were
significantly (p<0.05) higher in males than females during summer (on-set of breeding
season). Females were observed to have remarkably higher values (p<0.01) of erythrocyte
sedimentation rate, total leucocyte count and thrombocyte count during summer. The
reproductive biology of the mud eel and spiny eel have been described in terms of sexual
dimorphism, gonadosomatic index (GSI), ova diameter and fecundity. It was observed that
these species could be sexed on the basis of body colour during the breeding season. GSI
values showed peak during June (5.50, in male and 7.52, in female) and July (8.40, in male
and 10.58, in female) in the mud eel and spiny eel respectively. Monthly ova diameter measurement for both the species showed a progressive increase upto 4.0 mm and 1.0 mm
for mud eel and spiny eel respectively. The mean fecundity was determined for mud eel
and spiny eel to be 995 eggs and 4907 eggs respectively. The fecundity-gonad relationship
(Log F = 0.33+ 2.31 × Log GW) and fecundity-total length relationship (Log F = - 1.74+
3.30 x Log L) showed better performance as compared to other variables in the mud eel
and the spiny eel respectively. The results of culture experiment have been described in
terms of effect of different food items, different shelters and stocking densities on growth
and survival rate of the mud eel and the spiny eel. It was noted that among the food items
mud eel preferred dead small fish and spiny eel liked dead small shrimp. Water hyacinth
and PVC pipes were found to be the suitable shelters for the better growth and survival of
the mud eel and the spiny eel respectively. Among the different densities the mud eel gave
better growth and survival with higher stocking density (100 fish/1.25 m²), while the spiny
eel gave better growth and survival with lowest stocking density (20 fish/2.5 m²).