Abstract
Due to the importance of water variables conditions and available food in the development and survival of fish larvae, the current research evaluates the effects of two different food treatments (ration + zooplankton and only zooplankton) and water quality in tanks with Brycon orbignyanus larvae. Total water transparency (45 cm) has been mainly associated with short residence time, continuous water flow and shallowness. Dissolved oxygen ranged between 1.32 and 7.00 mg.L(-1) in tanks with ration + zooplankton and between 1.82 and 7.60 mg.L(-1) in tanks with only zooplankton treatments. Nutrients were directly affected by the addition of ration in water, with the exception of nitrite. Ten Rotifera species were found represented by high densities, ranging between 8.7 x 10(5) and 1.3 x 10(6) org.m(-3), throughout the experimental period (January to March/1996). Cladocera had the lowest density in the four tanks under analysis and ranged between 4.7 x 10(4) and 2.1 x 10(5) org.m(-3) for the six species. Diaphanosoma birgei has been classified as the most frequent species. Since ration + zooplankton produced better larvae yield, this treatment is recommended for Brycon orbignyanus larvae.
Highlights
A major problem in Brycon orbignyanus production is its high mortality rate during the larvae stage and during development into the fingerling stage
According to Ceccarelli and Senhorini (1996), other fish larvae should be placed together with B. orbignyanus larvae in order to avoid cannibalism during the incuba77
After this phase B. orbignyanus larvae may be transported to fishponds, culture success depends on the type and quantity of zooplankton available in the pond, larvae density and water quality
Summary
A major problem in Brycon orbignyanus production is its high mortality rate during the larvae stage and during development into the fingerling stage. Feeding preference of B. orbignyanus larvae consists of crustaBraz. J. Biol., 68(1): 77-86, 2008 cean zooplankton, mainly Cladocera and insect larvae. According to Ceccarelli and Senhorini (1996), other fish larvae should be placed together with B. orbignyanus larvae in order to avoid cannibalism during the incuba. After this phase B. orbignyanus larvae may be transported to fishponds, culture success depends on the type and quantity of zooplankton available in the pond, larvae density and water quality
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