Efeito da Chlorella sp. na dieta de larvas de paulistinha (Danio rerio)

Abstract

The zebrafish (Danio rerio) is a freshwater tropical fish, has omnivorous feeding habit, native of the rivers of south Asia. Supplements can improve the efficiency of the ration and increase growth and survival of cultured fish. Chlorella sp., green algae of cosmopolitan distribution, present mainly in the phytoplankton of lakes and lagoons, considered excellent source of protein, with favorable concentration of carotenoids, polysaccharides, vitamins and minerals, has been used in aquaculture as dietary supplementation in diets for various species of aquatic animals. The purpose of this work was to verify the effect of Chlorella as a food supplement on growth and survival of zebrafish larvae. To obtain the larvae, the matrices were reproduced in cages in the ratio of 3 females: 1 male. They were kept in a photoperiod of 14 h light/10 h dark, under constant aeration. The experiment lasted 21 days from the third day after hatching, when the larvae began to exogenous feeding. 144 larvae were distributed in a completely randomized design with three treatments and four replicates, and T1 - ration, T2 - 75% ration + 25% Chlorella and T3 - 50% ration + 50% Chlorella. The concentration of the food by aquarius/day was: T1 - 14 mg of ration; T2 - 10.5 mg of ration and 3.5 mg of Chlorella and T3 - 7 of ration and 7 mg of Chlorella, distributed in three periods (10, 14 and 17 h). The experimental units were used aquariums of 2L with 1.8 L of filtered water. It was carried out the monitoring of water quality: temperature (27±3ºC), dissolved oxygen (6.65 ± 1.15 mg/L.) and pH (6.9 ± 0.1). The daily changes of 70 % of the volume of water from the cultivation favored the permanence of oxygen concentration deemed acceptable for the species. The T3 (25 % of Chlorella) and T1 (Diet) presented the highest (75%) and lower (66.66%) percentages of survival, respectively. The growth of larvae was higher in T1, with a significant difference (p<0.05) in relation to the treatment T2 (50% of Chlorella). In this way, the Chlorella was efficient in feed supplementation for the survival of fish, whereas the commercial feed used in this experiment is a ration of quality protein and low in vegetables.