Comparison of muscle quality of rainbow trout (Oncorhynchus mykiss) raised in two open and partial water reuse systems

Abstract

Introduction: At present, many cold water fish farms in the country use reused water to
produce fish, but the effects of its use on fish muscle quality are not well known. The aim
of the present study was to compare the muscle quality of rainbow trout (Oncorhynchus
mykiss) raised in two open and partial water reuse systems.
Materials & Methods: For this purpose, young trout with a stocking density of 20 kg/m3
and a loading density of 1 L/min/kg of fish was studied in two an open system (100% makeup
water) and a designed partial water reuse system (with a reduction of 80% make-up
water and its replacement with the reused water) for 45 days.
Results: Four times of water recirculation caused an increase of 6.7 and 6.5 times in the
amount of water total ammonia and total phosphorus compared to an open treatment,
respectively. Muscle crude protein, crude fat, pH and moisture percentage showed
significant differences between two treatments. In contrast, there were no significant
differences in water holding capacity, cooking loss, texture analysis (hardness,
adhesiveness, resilience, cohesiveness, springiness, gumminess and chewiness) and color
indices of L*, a* and b* between two treatments.
Conclusion: Consequently, the reuse of water to the same extent as the present designed
protocol did not have very obvious changes on many studied muscle quality factors of fish.