Nutrient Digestibility and Retention of Potential Feed Ingredients for Rainbow Trout (Oncorhynchus mykiss W.) Aquaculture in Iran

Table 2

Experimental conditions of the three trials.

	Run 1	Run 2	Run 3
Volume (L)
Whole system		1,500
Aquarium		57
Water inflow rate (L/min)
Well water inflow into the system		6
Water flow to each aquarium		3
Water turnover rate (times/day)
Whole system		5.8
Aquaria		75.8
Water source		Preprocessed well water
Number of aquaria per diet		4
Type of aquaria		Rectangular glass, tapered bottom
Photoperiod (light:dark)		12 : 12 with LED light
Number of fish per aquarium		15
Room temperature (°C)		15
Average water temperature (°C)^†
Aquaria	12.8 ± 0.1	12.7 ± 0.1	13.2 ± 0.0
System inflow	13.0 ± 0.4	12.9 ± 0.3	13.0 ± 0.4
System outflow	12.8 ± 0.3	12.8 ± 0.2	13.0 ± 0.3
Dissolved oxygen (mg/L)^†
Aquaria	9.9 ± 0.1	9.9 ± 0.2	10.1 ± 0.0
System inflow	10.0 ± 0.4	10.1 ± 0.2	10.1 ± 0.2
System outflow	10.0 ± 0.3	10.1 ± 0.2	10.2 ± 0.2
pH^†	7.8 ± 0.1	7.9 ± 0.1	8.1 ± 0.1
NH4^+ mg/L^†	0.20 ± 0.3	0.07 ± 0.0	0.09 ± 0.0
NO2^− mg/L^†	0.31 ± 0.3	0.11 ± 0.1	0.23 ± 0.1
NO3^− mg/L^†	4.79 ± 1.2	<4.4 ± 1.2	4.5 ± 0.3
Average stocking weight (g)^†	18.9 ± 1.2	22.7 ± 2.2	12.0 ± 0.9
Initial average total length (cm)^†	12.3 ± 0.8	14.3 ± 1.1	10.7 ± 0.4
Stocking density (kg/m^3)	4.7	5.7	3.0
Feeding level (% biomass/aquarium)	1.5	2	2
Acclimation period (days)	5	4	3
Trial period (days)	56	30	56

^†Reported mean values with standard deviation (±SD).