Morphometric and meristic traits of giant sea catfish <em>Arius gigas</em> (boulenger 1911) from new Calabar river and Degema River, Rivers State, Nigeria

Morphometric and meristic characters of the Arius gigas species were examined from two study areas (New Calabar and Degema Rivers) for a period of six months in Rivers State, Nigeria. Total of 200 individuals, 100 from each study site, were examined and analyzed. A majority of the values for external morphometric parameters of A. gigas were higher in the New Calabar River than those from Degema River population, with no significant differences exist (p<0.05) across the morphometric parameters except for pre-orbital length, post-orbital length and eye length. The meristic characters revealed variations in the mean values of dorsal fin spine (8.55±0.11 and 7.07±0.38), pectoral fin ray (5.96±0.06 and 4.23±0.26), and pelvic fin ray (14.99±1.21 and 7.51±0.52) in the study. A significant difference was noted in the number of dorsal fin spine (p< 0.05) between the two populations. The mean percentage of the Length of caudal peduncle (LoCP),1st and 2nd dorsal fin (DF), length of interdorsal fin (LoIDF) and length of adipose fin (LoAF) of A. gigas in the New Calabar River were significantly higher (p<0.05) than Degema River. Growth variability for standard length and all external parameters displayed allometric growth of A. gigas from Degema River. Further studies are recommended to corroborate the findings of the two populations using molecular markers for making conservation plans for exploitable A gigas species.