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Abstract:Length-weight relationship of Amblyceps apangi had been carried out from streams of Dikrong River Arunachal Pradesh, during January 2014 to December 2015. The co-efficient of regression (b) was recorded as 2.213 (males); 2.376 (females); 2.312 in pooled (both sexes). The result reveals that females have better growth than males and both sexes signify a negative allometric growth pattern. The highest Condition factor 'K' value (0.82 ±0.24) for male was found in November and minimum (0.45 ± 0.12) was observed in July. In case of female, the highest value (0.95 ± 0.11) was recorded in November and lowest (0.50 ± 0.09) was noticed in June. Again, the highest K values (0.83 ± 0.16) of male was found in 61-70 mm while in females the highest (0.86 ± 0.13) was in 51-60 mm. The lowest values for both male (0.38 ± 0.07) and female (0.36 ± 0.03) were observed in 141-150 mm. The Relative Condition factor (Kn) value did not show any variation with respect to monthly and size grouping. The result indicates that both the sex was found in a good condition. Moreover, the K values were encountered with GSI values during the quiescent and degenerative phases of the reproductive cycle but minimum K values coincides with the increased GSI during the recrudescent phases both the sexes. Coefficient of correlation (r) shows more or less similar trend in all male, female and pooled. The correlation coefficient 'r' was found to be 0.906 (males); 0.949 (females) and 0.934 (pooled). This result indicates that there was a good correlation between length and weight of the fish.

Amblyceps waikhomi sp. nov. is described from the Nongkon stream which drains into the Noa Dehing River, a tributary of the Brahmaputra River, in Arunachal Pradesh, India. The new species can be distinguished from congeners (except A. torrentis) in having a deeper body depth at anus. It further differs from congeners (except A. mangois and A. serratum) in having fewer vertebrae, from A. mangois in lacking (vs. having) strongly-developed projections on the proximal lepidotrichia of the median caudal-fin rays, and in having a longer, wider, and deeper head; and from A. serratum in having a posteriorly smooth (vs. with 4–5 serrations) pectoral spine, and unequal jaw length (lower jaw longer and weakly-projecting anteriorly vs. equal upper and lower jaws). It additionally differs from A. murraystuarti, A. torrentis, A. apangi, A. laticeps, and A. cerinum in having a deeply forked (vs. emarginate or truncate) caudal fin. This species is the seventh amblycipitid species known to occur in the Ganga-Brahmaputra River system.

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