1、尾形南方大口鲶的幼鱼到孵化后的30—40天(全长35—40mm),其尾鳍的上叶就明显长于下叶(此性状一直保持,被作为与鲶成鱼区别的特征之一);而鲶的尾鳍上、下叶等长,是对称的。2、体色南方大口鲶和鲶幼鱼体侧和背部呈黑灰色,前者有时略泛黄色,后者有时带深黑绿色.两 (1) The larvae of the caudal southern catfish are 30 to 40 days after hatching (35-40 mm in total length), the upper leaves of the caudal fin are significantly longer than the lower lobe (this trait has been maintained as a distinguishing feature from catfish) One); and catfish caudal fin, the lower lobe isometric, is symmetrical. 2, body color South catfish and catfish juvenile body side and back were dark gray, the former slightly yellowish sometimes, which sometimes dark green with two.