This study was carried out on the rancidity situation of fish sold in Mubi markets, Adamawa State
Nigeria. Standard methods were used in data accumulation. Fish market at Mubi was visited during the month
of July and August and the smoked, dead, dried and frozen fish were sampled and analyzed for peroxide value.
There was low association between the smoke and dead Clarias and Tilapia and between the dried and frozen
fish (Mormyrus rume and mackerel) sold in the markets in the month of July. Though the paired t-test value of
t= 10.524 df = 1, P = 0.051 was recorded of smoke and dead fish and t= -11.211 df=1 was recorded for dried
and frozen fish. The association between the peroxide values of smoked and dead fish sold in the market in the
month of August was r=0.8, P=0.001 and frozen r=0.57 P=0.01 and the paired t-test association if t= -13.285
P= 0.001 shows a significant difference. The smoked and dead fish have correlation value of r=0.7 P=0.01 with
t-value of t=-10.54, P=0.10 showing a significant difference between their peroxide value. There was
correlation r= 0.6 between the smoked and dead fish with t-value of t= 28.08, P = 0.028 showing a significant
difference between peroxide values of Clarias in the market. The dried and frozen fish peroxide values were not
significantly different as well as the smoke and dead fish. The same relationships were recorded for smoked and
dead Clarias and Tilapia, dried Mormyrus rume and frozen Mackerel. Based on the result of this study peroxide
values varied with fish species and size. The dead fish had higher values than those processed. The health
problems associated with rancid fish are highlighted.