46 SEPTEMBER 2017 • WORLD AQUACULTURE • WWW.WAS.ORG water sterilizer, heat pump and water pump (Fig. 2). Sampling was performed monthly (Fig. 3) and the daily water exchange rate was 10-20 percent. Feed was supplied to apparent satiety or ad libitum with extruded pellets1 from 0.84 to 2.1 mm particle size. Feed was provided four times per day, between 2 and 4 percent of total biomass. In addition, physicochemical parameters were monitored daily. At PDFSA, commercial juvenile culture was carried out in six fiberglass tanks of 1500 L coupled to two RAS (Fig. 4). These systems consisted of a sedimentation tank, sand filter, biological filter, degasser and UV sterilizer. For maintenance of the system, water was replaced at 15 to 20 percent/d, with biweekly sampling during the culture period (Fig. 5). Extruded pellets of 1-2 mm particle size (Otohime1, Aquaxcel®2 and Nicovita3) was supplied ad libitum three to six times, depending on consumption. Water temperature in all systems was maintained between 19-22 C and was relatively stable in all systems, with the greatest variation in the static system (Fig. 6). Average temperatures were 20.5 ± 1.0 C, 21.1 ± 1.1 C and 19.8 ± 0.7 C in SS, RAS-L and RAS-C, respectively. Thiese temperatures are greater than those (14.9-17.3 C) used by Silva (2001), whose flatfishes reached the commercial size of 1 kg in 3.5 years. Wasielesky et al. (1998) observed that juveniles of P. orbignyanus accepted feed at a temperature range of 10-27 C, with an optimum temperature range in the pre-fattening period of 18-21 C. It is important to determine species-specific optimal temperature ranges at each stage of the life cycle. Mean values of dissolved oxygen concentration were 7.7 ± 0.6 mg/L, 6.2 ± 0.6 mg/L and 5.7 ± 1.1 mg/L in SS, RASL and RAS-C, respectively. Average values of pH were 7.7 ± 0.3 and 7.3 ± 0.7, in the SS and RAS-L, respectively; this parameter was not measured in the RAS-C. In all culture systems, total length (cm) and weight (g) were TABLE 1. Larval and post-larval culture protocol of the flatfish Paralichthys adspersus under laboratory conditions at IMARPE. DPH Water FEEDING Bottom Cleaning exchange(%) Microalgae Rotifers Artemia sp. Microdiet siphoning of the tank Larval Phase 1 - 5 0 x x 6 50 x x 7 - 10 0 x x 11 10 x x 12 - 14 15 x x 15 - 20 20 x x x x 21 - 23 50 x x x x x 24 - 27 100 x x x x x 28 - 40 100 x x x Post-larval Phase 40 - 50 100 x x x x 50 - 60 100 x x x TABLE 2. Larval and post-larval culture in Paralichthys adspersus at PDFSA. DPH Water FEEDING Bottom Cleaning exchange(%) Microalgae Rotifers Artemia sp. Microdiet siphoning of the tank Larval Phase 1-3 0 x x 4-10 10 x x 11-14 25 x x 15 25 x x 16-19 30 x x 20-23 40 x x x x 24-26 50 x x x x x 27 70 x x x x 28-35 100 x x x x Post-larval Phase 35-50 100 x x x x 50-60 100 x x x
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