Trairao (Hoplias lacerdae) larviculture in slightly saline freshwater

The objective of this work was the development of larviculture handling technics to rear trairao in slightly saline freshwater, with Artemia nauplii as live food. At the beginning of exogenous feeding, eight days after hatching, trairao larvae were counted and stocked in twelve 1.5-L vessels, equipped with aeration, at 10 larvae/L density. The vessels were distributed in three 130-L tanks filled with controlled temperature water (29.5degreesC). The tanks were covered with black plastic to keep the environment dark, and uncovered only for daily management. The larvae were submitted to three treatments with four replicates, as follows: freshwater culture; water with 2parts per thousand salinity; and water with 4parts per thousand salinity. For the first five days, larvae were fed 300 Artemia nauplii/larvae. In the subsequent five days, larvae were fed 600 Artemia nauplii/larvae, and from the 11(th) to the 15(th) day, 900 Artemia nauplii/larvae, divided in three portions. At the end of the experiment, survival, growth (length and weight), specific growth rates and stress resistence rate were evaluated. At the end of 15 days of culture, no significant differences were observed among analyzed results of the different treatments. Rearing conditions were efficient, with high survival rates (average values superior than 91,6%), and Artemia proved to be an attractive food. Salinity levels studied did not affect trairao larvae and fingerling development compared to freshwater.