In this study unicorn leather jacket (Aluterus monoceros) fish skin collagen was hydrolyzed with the crude collagenase extracted from the fish fins discarded as by-product at three different temperature viz. 50C (CP-5), 250C (CP-25) and 500C (CP-50) to obtain collagen peptide of three molecular mass fraction viz. <3kDa, <10kDa and <30kDa by ultra-filtration using Tangential flow filtration system. The collagenase extracted from fins had a MW of 29kDa and hydrolyzed skin collagen to molecular masses below 20 kDa efficiently with a DH ranging from 6.5-7.7%. CP-5 peptides with <3kDa showed the maximum antioxidant activity. DPPH and hydroxyl radical scavenging activities were good with 70% and 68%, respectively; while metal (Fe2+) chelating activity was 33% and FRAP activity was 0.03315. In-vitro gastro intestinal digestion study indicated that after pepsin digestion the resultant protein in the digest was more in CP-5 than CP-25 and CP-50. The rate of peptide absorption of the CP was significantly high in <3kDa CP-50 (32.93%), followed by CP-25 (32.66%) and CP-5 (32.56%) after gastric and pancreatin digestion. CP-5 of <3kDa having better antioxidative activities of collagen peptides in invitro gastro intestinal digests than CP-50 of <3kDa. Hence, it is recommended to produce collagen peptides from fish skin wastes at low temperatures rather than at 500C to retain good biological properties. The study thus indicated that CP with good antioxidant activity shall be produced by hydrolysis the skin at 50C, rather than at 500C.