ANALYSIS AND COMPARISON OF MORPHOLOGY AND CYTOLOGY BETWEEN THE F1 HYBRID CATFISH(CLARIAS FUSCUS�i>C. LAZERA) AND ITS PARENTS

Analysis and comparison of morphology and cytology were made between the F1 hybrid catfish (C. fuscus?i>C. lazera) and its parents using conventional and karyotype analysis methods. The results are as follows: Almost all morphological traits of the hybrid show the characteristics of both parents. The hybrid is closer to the female parent (C. fuscus) in 3 countable characters and 6 typological characters, and to the male parent (C. lazera) in one countable character and 8 typological characters. Some important typological characters, e.g., body height/total length and body width/total length, in the hybrid are closer to those in the female parent. The hybrid is also similar to the female parent in condition factor. The male hybrid is sterile. The karyotype of the hybrid has the characteristics of both parents. The chromosomes (2N=56) can be classified into 2 groups i.e., group F and group L, which have the same chromosome sets of the female and male parent respectively.Some univalents, bivalents and multivalents in ring or chain shape are observed in metaphase I in the hybrid. Some problems about the evolution of the parent's karyotype and the factor causing the sterility of the male hybrid are also discussed.