Abstract: Sixteen samples of Skip Jack Tuna (Katswonus pelamis) with a size range of 9.58-1.62 gm werecollected at the Lagos Jetty of the Nigerian Institute for Oceanography and Marine research, Victoria Island, Lagos and stored at a cold storage temperature of-21� for a period of 13 weeks. Samples were kept in the cold room for 6 weeks before the commencement of the experiment using one piece of fish per week for both organoleptic and chemical studies (Trimethy lamine (TMA), Total Volatile Bases (TVB) and Free Fatty Acids (FFA). This is in a bid to determining the level of spoilage and limit of acceptability (Shelf life) of the fish. Organoleptic assessments of a five-man panel, showed the general conditions (appearance, taste and odour) of the fish was unsatisfactory at the end of the 12th week of storage, with an average score of 3.9`0.30. However the uncooked fish was still acceptable (4.5`0.33) up till the 11th week of storage. Also for the cooked specimen the general conditions (texture, odour and taste) of the fish were unsatisfactory at the and of 12th week, with an average score of (4.6`0.38). The chemical assessment results were significant (p<0.05) and there was a strong positive linear correlation (TMA = 0.9823, TVB = 0.9855 and FFA = 0.9847) between the chemical indices and the length of storage. For the TMA and TVB, the limit of acceptability was the 8th week of storage with values of 4.0 mg 100 g^-1 fish and 3.75 mg 100 g^-1 fish, respectively. With FFA as a chemical index of spoilage, (a less sensitive index) acceptability limit of 1.07% was recorded at the 11th week of cold storage. The limit of acceptability (shelf life) for the cold storage of Tuna (Katsuwonus pelamis) as shown in this study is between the 8th and 11th week of storage at-21�C using the chemical assessment (as the lower limit) and organoleptic assessment results (as the upper limit) as indicators. However using Least Significant Difference (LSD) to test, the shelf life of Tuna under cold storage of-21�C is 2 months.