Fig. 6. Radioactivity of iodide, thyroid hormone and thyroid hormone conjugates fractions, shown as the percentage of the total dose remaining in the fish at the time of sampling per gram of tissue, in the subpharyngeal region (A), kidney (B) and head kidney (C), after Sephadex LH-20 chromatography at 2, 24, 48 and 96 h after i.p. ¹²⁵I injection in tilapia (•, N=6) and carp (, N=6). Results are means ± s.d. One-way ANOVA was used for statistical evaluation. Significantly different levels of radioactivity compared with that at 2 h are indicated for tilapia (^*P<0.05, ^**P<0.01, ^***P<0.001) and carp (+P<0.05, ++P<0.01, +++P<0.001).