Morphological structure and karyotype of Osteoglossum bicirrhosum

Abstract:

The morphological structure and karyotype of Osteoglossum bicirrhosumwere studied. The fish has a laterally compressed body covered with silver scales, a point large mouth and two well developed lateral lines with 35-36 scales. Gill rakers are short and sparse. The soft fin rays are D43-46, P7, V6, A50-54, C12 respectively. The body length is 5.34, 5.23, 97.62 and 1.82 times of body height, head length, tail handle length and tail length respectively; the head length is 3.95, 6.04, and 2.96 times of snout length, eye diameter and diameter between eyes respectively; the body height is 2.05 times of body width. No sexual dimorphism has been found. The fish has a very developed stomach with “U” shape and two pyloric caeca. The swim bladder, length of which is equal to that of body cavity, has one room and is located above body cavity as well as adjacent to vertebra. Both male and female have unilateral gonad and eggs of mature females are fewer, but bigger. The number of chromosome is 2n=56 and the karyotype is 2n=2sm+26st+28t, NF=58. No cytologically distinguishable sex chromosome has been found.