We investigated methods for extracting histidine-containing low-molecular-weight (LMW) peptides such as anserine, carnosine and histidine from the edible meat of tuna byproducts. Extracts were treated by several methods including heat treatment ($80^{\circ}C$, 10 min), DOWEX ion exchange (IEC), ultrafiltration (UF), and carboxymethyl (CM)-cellulose column chromatography (IEC+CMC); then the levels of protein, total iron, histidine, carnosine, and anserine were measured. Extracts treated with IEC+CMC using CM-cellulose were analyzed for total iron, protein, histidine, and anserine content, which were $6.27{\pm}0.26mg/mL$, $5.20{\pm}0.21{\mu}g/mL$, 0.80 mg/mL, 0.208 mg/mL, and 4.40 mg/mL, respectively, in yellowfin tuna; and $9.05{\pm}0.82mg/mL$, $4.06{\pm}0.20{\mu}g/mL$, 1.62 mg/mL, 0.012 mg/mL, and 7.28 mg/mL in bigeye tuna. By comparison in IEC-UF treated extracts, protein, total iron, and histidine content decreased by 43%, 73%, and 27% in yellowfin and 0.4%, 54%, and 23% in bigeye tuna, wheres carnosine and anserine content increased by 22% and 17%, respectively. Freeze-dried (FD) extracts exhibited similar trends as non-dried extracts, i.e., dipeptide content increased with purification steps, whereas pro-oxidant (total iron and protein) content decreased. IEC+CMC treated FD extracts had the highest anserine, content, and the greatest reductuion in pro-oxidants.