Tilapia producers in Latin America are adopting the In-Pond Raceways System -IPRS- but need a good comparison between traditional earth pond stocking and IPRS. This study evaluated two traditional ponds with high stocking densities 5.5 fish/m² (treatment TA), fish initial weight of 11 grams, final harvest weight of 488.5 grams; two ponds with low stocking densities of 3.9 fish/m² (treatment TB), fish initial weight 20 grams, harvest weight 1143 grams and one pond with four IPRS units, initial weight 49.2 grams, harvest weight 589 grams. ANOVA analysis show a variability among treatments, in harvest weight, culture days, weight gain (P-value <0.05) and FCR (P-value >0.05) see tables below.
TA average tilapia production was 14,657 kg/Ha/Harvest in 230 days, TB was 26,576 kg/Ha/harvest in 247 days and IPRS was 36,971 kg/Ha/harvest in 146 days with (t=0.045) for TA, TB and IPRS respectively. Weight gain in grams/day TA = 2.12, TB 4.74 and IPRS 3.69. FCR TA = 1.07, TB = 1.31 and IPRS = 1.29, showing better results for TA, but data indicate that feed regime was decrease because endemic low DO, due to high stocking densities.
Dissolved oxygen in treatments TA and TB were kept in concentration above 4.0 mg/L on the first 5 months, descending at values between 1 – 2 mg/L on the rest of the culture period, meanwhile in IPRS DO levels were kept above 3.0 mg/L dropping to 1 -2 mg/L on few occasions.
This research was originally planned to have to have vaccinated and non-vaccinated fish as treatment, unfortunately vaccinated fish show high mortalities due to handling and extra un-vaccinated fish was needed to be stock on top of the already vaccinated.
Feeding rates for TA = 70.98, TB = 147.9 and IPRS 247 kg/Ha/day. Survival percent of stocking as follow: TA = 73.5, TB = 76.6 and IPRS = 61.8 The latest treatment, survival was low due to uncounted initial mortalities. Overall high productivity of the IPRS system is due to it capacity to extract fish waste out of the aquatic environment, maintain a better water quality, higher concentrations of dissolved oxygen. Results show that in traditional earth ponds, stocked at more than 4 fish/m² negatively affect fish production, weight gain and culture days, however IPRS technology is an option for water conservation, bird predation, better yields.