Enriched Artemia Nauplii with Commercial Probiotic in the Larvicul- ture of Angelfish Pterophyllum scalare Lichtenstein (1823)

Natalino da Costa Sousa José Araújo da Silva Emilly Monteiro Lopes Arthur Felipe Lima dos Santos Francisco Alex Lima Barros Carlos Alberto Martins Cordeiro Peterson Emmanuel Guimarães Paixão Estela dos Santos Medeiros João Carlos Nunes de Souza Márcia Valéria Silva do Couto 1. Federal University of Pará (UFPA), Campus Bragança, Alameda Leandro Ribeiro, Bragança, 68600-000, PA, Brazil 2. Tiradentes University (UNIT) Av. Murilo Dantas, 300 Farolândia, CEP 49032-490, Aracaju, Sergipe, Brazil 3. Faculdade Pio Décimo Av. Pres. Tancredo Neves, 5655 Jabotiana, 49095-000, Aracaju – SE. Brazil


Introduction
O rnamental fish trade around the world has becomes a profitable activity moving approximately US 15 million [1,2] . Currently, it market look for several fish species with highest quality, different shape and colors [3,4] . Among the native fish species from Amazon, the angelfish Pterophyllum scalare has economic potential into national and international market due to this varied patterns and colors required by the ornamental market [4,5,6] .
In freshwater ornamental fish, the larvaculture remains as the most problematic phase of production with highest mortality rate caused by management, inadequate nutrition and stocking density [4,7,8] . These factors can reduces its productive performance and health of the larvae [4,5,9] .
The larval phase, live feed have an important paper to supply the nutritional requirement and its development [8] . Currently, the ornamental fish sector use widely artemia nauplii due to the size, protein and lipid profile as well as enzymes that aid its digestion process [10,11] . In the last de-cade, fish farmers has applied different strategies for larvaculture to improve the performance and health [8,12,13,14] . Among the new strategies, enriched artemia nauplii with probiotic showed nice results about the productive performance, survival, improvement of immunological system and intestinal modulation [9,15,16,17,18,19] .
In front this, enriched diets for ornamental fish larvae becomes an efficient strategy in captivity rearing. Nonetheless, still missing scientific data about the use of probiotic for larval diet. Thus, this study evaluated the effect of enriched artemia nauplii with commercial probiotic for angelfish larvae Pterophyllum scalare determining performance, survival and intestinal modulation.

Intestinal Microbiota
For determine bacterial amount in the intestine from post larvae, its intestinal tract (pools of five larvae) macerated with sterile saline solution 0.65% passed by serial dilution (1:10 factor). An aliquot (100 µL) from each of three dilutions (10 -1 , 10 -3 and 10 -5 ) was used to inoculate petri dishes containing either Triptone Soy Agar (TSA -incubated at 30 ºC for 24 hours) to obtain counts of total heterotrophic bacteria, or MRS Agar (incubated at 30 ºC for 48 hours) to obtain counts of lactic acid bacteria [19] .

Growth Perfomance
At the end of experiment, all post larvae passed per biometric procedure to determine weight and length evaluating: Total length (TL), final weight (FW), weight gain (WG), specific growth rate (SGR), survival (S), uniformity (U) [21] and relative condition factor (Kr) [22] .

Statistical Analysis
Data was tested for normality (Shapiro-Wilk) and homoscedasticity (Levene's). Subsequent analysis of variance tests were performed applying post hoc Tukey tests for separation of means (P<0.05) [23] . Microbiological counts showed non-parametric characteristics and were therefore log transformed [logX10 (x+1)] and arc sen square root (x).

Discussion
The use of bacteria with probiotic potential has showed positive results to the ornamental aquaculture [9,17,24,25] . Nonetheless, still missing reports about their use for angelfish larvae on productive performance, intestinal modulation and survival.
Colonize the intestinal tract stands out as the main aspect to determine its probiotic potential [19,26] . For this study, the artemia nauplii works as transporter of probiotic bacterium to the host. Its intestinal tract reduced the heterotrophic bacteria amount with the increases of probiotic bacterium due to the competition for space, nutrients and releasing of bactericides [15,19,27] . [17] reported it modulator effect in the intestine for angelfish adult, as also to Carassius auratus [24] and Xiphophorus helleri [25] . In addition, probiotic act as immune stimulant forming barriers against pathogenic bacteria and increasing its defense cell numbers [16,19,25,28] . Thus, it increases above 80% of survival could be related to the effects of probiotic bacterium included in the exogenous diet during larvaculture.
The larval performance improved in this study with the enrichment of artemia nauplii promoting greater weight gain, specific growth rate and survival. It benefits would be related to the intestinal modulation that provides increased intestinal villi and better nutrient absorption [9,19] . According to [29] , they observed similar result with increased performance for angelfish larvae Pterophyllum scalare using a different commercial probiotic.
For these reasons, enrichment of artemia nauplii becomes an efficient strategy to ornamental fish farming considering the probiotic amount to reach its benefits results. However, its microorganisms could influenced by environmental factors, age, development phase and physiological aspects [19,30,31,32] .

Conclusion
The enriched artemia nauplii with commercial probiotic (3g/L) can modulates the intestinal tract, increases the per-formance and survival. Thus, it enriched diet can be used as a new strategy for larvaculture of the angelfish larvae Pterophyllum scalare.

Conflicts of interest
The authors have no conflicts of interest to declare.