Effects of colored light and tank color on growth indices and some physiological parameters of juvenile beluga (Huso huso)

Abstract

International SturgeonResearch Institute, Guilan, IranSummaryThe influence of colored light and tank color was investigatedon growth performance (body weight, growth rate, carcasscomposition, etc.) and physiological status (blood and plasmaparameters) of beluga (Huso huso) juveniles. The study wasconducted using 64 specimens for colored light treatments withinitial weight 98.83 ± 1.42 (mean ± SE) g which were rearedunder white, red, green and blue light and using 80 specimensfor tank color treatments with initial weight 98.50 ±1.24 (mean ± SE) g which were reared in white, red, green,black and blue tanks, all for 12 weeks. Red light had asignificantly negative impact on beluga growth performance(in contrast with blue light) accompanied with reduced livertotal lipids and plasma albumin and elevated plasma cortisol,glucose, cholesterol and triglyceride (in contrast with the othertreatments). No significant effects of tank color were detectedon growth performance. Nevertheless, most of growth param-eters suggested a positive impact of black tank. Althoughplasma glucose levels in white tank were significantly higherthan the other tank colors, no significant effects of tank colorwere detected for the other physiological parameters. There-fore, based on the obtained results, blue light by establishingcomfort in beluga juveniles spelled increased growth perfor-mance and had positive significant effect on physiologicalconditions. Moreover, taking into consideration the consis-tency of all growth parameters among beluga juveniles rearedin black tanks, it is suggested that considerable results inregard to this treatment may be achieved if the rearing periodprolongs.IntroductionThe living fossil status of the lineage and the unusualmorphologic traits of sturgeons make the research on themscientifically valuable (Gardiner, 1984; Bemis et al., 1997).Caspian Sea is the habitat for the four commercial species ofsturgeon (Khodorevskaya et al., 1997) where their populationsare declining due to overfishing for meat and caviar produc-tion, habitat destruction, and environmental pollution (Billardand Lecointre, 2001). The beluga, Huso huso, is an importantcommercial species in the Caspian Sea and a good candidatefor aquaculture because of their fast growth, market price,propagation in captivity and high marketable value of theircaviar. In order to optimize the cultivation of this species,realizing its behavior and performance in culture conditions issubstantial. Among environmental factors that may influencefish performance in culture are colored light and tank color(Barton, 2002). The effects of colored light on disparate aspectsof fish physiology have been investigated such as growth,survival, neuro-hormonal system, reproduction, behavior andstress response (Head and Malison, 2000; Ruchin, 2001, 2004;Volpato and Barreto, 2001; Bayarri et al., 2002; Naor et al.,2003; Boulcott et al., 2005; Marchesan et al., 2005; Karak-atsouli et al., 2007, 2008). Each of the above studies has beenindicated that various light colors have relieved the physio-logical processes in different species. Hence, it is likely that thisspecies-specific quality relates to consistencies of fish visualstructure with its particular natural habitat traits. The effectsof tank color on different aspects of fish physiology have alsobeen investigated including growth performance, survival, skincolor and stress response (Papoutsoglou et al., 2000, 2005;Tamazouzt et al., 2000; Rotllant et al., 2003; Van der Salmet al., 2004; Jentoft et al., 2006; Strand et al., 2007). Thesestudies have indicated that reactions to tank color may varyaccording to fish species and life stage (Papoutsoglou et al.,2005). While light is easily adjusted in intensive indoor fishcultivation and it is possible to have tanks manufactured inany color, determining suitable light and tank color forfarming beluga is important for optimizing its production andcomfort. The present study aimed to investigate whethercolored light and tank color could affect beluga growthperformance and physiological status (blood and plasmaparameters). For this reason, fish were reared separately underwhite, red, green and blue light and in white, red, green, blackand blue tanks.Materials and methods