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The yellowfin, Neothunnus albacora, which were caught on Indian Ocean in 1956 by a longliner, Bochomaru, were subjected to 45- to 60-day storage in CTC-ice (about 3 to 5ppm.) aboard the boat after being dipped in or smeared with CTC-containing sea water. The freshness of fish in each group was estimated after landing by organoleptic grading and volatile bases nitrogen content of the flesh. The skin and flesh of sample fish were assayed microbiologically for CTC residue, and the flesh was also assayed for residual CTC after boiling. The results can be summarized as follows: 1. The freshness of fish after landing was the best in a group which had been iced after being either dipped in CTC (10ppm.)-sea water for 1 to 4 hours or smeared with CTC (10 and 100ppm.) -sea water. The second quality was found in a CTC-iced group without any previous treatment (Table 1). 2. When the fish one from each experimental group, was stored at 0 to 15°C after landing, the fish which was CTC-smeared and CTC-iced showed storage life of about 138% and CTC-iced fish without smearing showed that of 125% as compared with that of control fish. 3. The price of the fish which were stored in CTC-ice with and without previous chilling after being killed on the deck was exceedingly high as compared to the price of the fish which were dead when hauled and that of the fish which were left standing for one hour on the deck after being killed (Table 3). 4. The skin of fish which were smeared with CTC (100ppm.)-sea water and stored in CTC-ice for 60 days possessed 0.34mcg. CTC per g. The flesh, 1cm thick beneath the skin of the same fish, contained 0.28 to 0.59mcg. CTC per g. 5. The residual CTC in belly fillets after 3-minute boiling was found 20 to 40% of raw tissue. Negative result was obtained (lower than 0.04mcg. per g.) after 5-minute boiling (Table 4).