Sarotherodon knauerae sp. nov. is distinguished from all congeners by the possession of an inflated second pharyngobranchial element in the upper pharyngeal jaw, and is one of the smallest known Sarotherodon, reaching a maximum observed size of only 75.2 mm SL. It further differs from sympatric S. lamprechti sp. nov. in possessing a terminal (vs. prognathous) mouth, scaled pectoral fin base, short pectoral fins ending at or in front of anus (vs. reaching first anal fin-spine or beyond) and short pelvic fins ending well in front of anus (vs. reaching anus). Additionally, S. knauerae possesses a shorter upper lip (19.1–25.4 vs. 22.5–28.4 % HL), a higher total gill raker count (24–30, mode 28 vs. 20–25, mode 22), and larger eyes (24.0–31.2 % HL, mode 27.3 vs. 20.4–29.2 % HL, mode 22.8). Distinguished from neighbouring riverine S. galilaeus populations (Cross, Wouri & Lower Niger), S. g. multifasciatus and S. g. borkuanus by a shorter anal fin (12.0–14.6 % SL vs. 15.3–19.3 % SL / 15.1–25.7 % SL and 13.4–17.9 % SL) and narrower caudal peduncle (12.8–14.5 % SL vs. 16.0–18.7 % SL / 13.9–18.3 % SL and 13.6–17.4 % SL). It differs from S. caroli and S. linnellii in higher gill raker counts (24–30 mode 28 vs. 18–20 mode 19 / 15–18 mode 18), from S. g. sanagaensis in a lower preorbital depth (17.8–23.0 vs. 25.0–27.8 % HL) and from S. g. boulengeri and riverine Sarotherodon galilaeus in a lower body depth (36.5–43.9 vs. 44.5–50.0 % SL and 43.5–44.6 % SL). Finally it differs from all other Lake Barombi Mbo Sarotherodon in a higher number of dorsal fin-rays (13 or 14, mode 13 vs. 10–12, mode 11) (Ref. 86429).