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A comparison of recirculation aquaculture systems versus biofloc technology culture system for on-growing of fry of Tinca tinca (Cyprinidae) and fry of grey Mugil cephalus (Mugilidae)

The IRTAmar® RAS systems, recirculation modules capable of recycling up to 0.5 kg of food with
a protein level of 50 % and volumes of 4,500 L per hour, were used for the trial. Each module is
composed of sand and cartridge filters (5 μm), a biological filter (submerged bed), an ultraviolet
filter (60W) and sensors for measuring dissolved oxygen, temperature and water flow levels. The water recirculation rate wasset at twice the volume of each unit per hour (180 L/tank/hour),
at a renewal rate of 10% of the total volume per day (9 L/tank/day).

For the BFT culture system, the biofloc did not come from an initial inoculum, but it was formed de novo due to the contribution of food and the absence of water renewal in tanks, which stimulated microbial growth and biofilm formation. The activity of the heterotrophic bacteria was stimulated with the daily addition of anhydrous glucose (organic carbon content = 46%). To calculate the amount of carbohydrate to be added, the criterion recommended by Avnimelech (1999) was followed.

In some cases, when total ammonium reached a concentration higher than 6 mg/L, 50% of the volume of water was renewed. Decanters with capacity equal to that of the culture tanks were driven through air-lift when the total solids concentration exceeded 500 mg/L. Due to the natural production of epidermic mucus by tench juveniles, cotton strips (10% of the surface area) were introduced into the on-growing tanksto trap the accumulated mucus and to promote the growth of biofilm (Bratvold and Browdy, 2001, Browdy and Moss, 2005, Schveitzer et al., 2013).

Vinatea, Luis, Jesús Malpartida, Ricard Carbó, Karl B. Andree, Enric Gisbert, and Alicia Estévez. 2018. “A Comparison Of Recirculation Aquaculture Systems Versus Biofloc Technology Culture System For On-Growing Of Fry Of Tinca Tinca (Cyprinidae) And Fry Of Grey Mugil Cephalus (Mugilidae)”. Aquaculture 482: 155-161. Elsevier BV. doi:10.1016/j.aquaculture.2017.09.041.

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