Ammonia and nitrate production of rainbow trout (Oncorhynchus mykiss) fed with different levels of earthworm (Eisenia fetida)

This experiment was designed with the aim of effecting the use of live Eisenia fetida as a food supplement on the water quality of rainbow trout rearing tanks. Fishs with an average weight of 58 g were placed in a completely randomized design in 4 treatments and each in 3 replicates. The fishes fed with different levels of 0, 25, 50 and 75%(control, T1, T2 and T3) of diets from live worms (including 50% moisture content) for 8 weeks at 18 °C. At the end of the experiment, water qualitative factors including PH, DO, TSS, TAN, NO2-, NO3- and temperature were measured. Comparison of the mean obtained from these factors showed a significant difference of pH between the control group and the other treatments, DO and TSS between all treatments (P<0.05). TAN in the first sampling of the above treatments had significantly different (P<0.05), but these results at the last sampling showed no statistically significant difference between treatment 2 and 3. Study of NO2- and NO3- in all sampling showed a significant difference between treatments (P<0.05).

Keywords:

Oncorhynchus mykiss , Eisenia fetida , Water quality , Ammonia , Nitrate