For the production and commercialization of ornamental fish species, it is indispensable to collect biometric data for the selection of animals for trade and genetic improvement of the stock. However, during handling processes, fishes receive more stress if proper anesthetics are not used. Thus, using appropriate anesthetics is an important tool for minimizing stress in animals. The objective of this study was to determine the effective concentrations of benzocaine, eugenol and menthol for angelfish (Pterophyllum scalare) anesthesia and to develop induction and recovery response curves for different concentrations of these anesthetics. A total of 75 fish were exposed to five concentrations of three different anesthetics, benzocaine (60, 85, 110, 135 and 160 mg L⁻¹), eugenol (40, 80, 120, 160 and 200 mg L⁻¹) and menthol (50, 75, 150, 200 and 250 mg L⁻¹) in a completely randomized design. Each concentration (5 fish per concentration) consisted of five replicates and each replicate was represented by a single fish (1 fish per replicate). The results indicate that the tested substances have met the criteria of anesthetic efficiency. The effective concentrations of benzocaine, eugenol and menthol determined to be 89.25 mg L⁻¹, 90.6 mg L⁻¹ and 92.1 mg L⁻¹, respectively for the anesthesia of freshwater angelfish.

A single farmed fish species assimilates about 20% of the nutrients in the supplied diet. This study evaluated if the culture of complementary ecological-function species can recover nutrients dispersed into water and transform them into high-valued biomass. A completely randomized experiment was designed with three treatments and four replications of each production system: monoculture of lambari (Astyanax lacustris); integrated aquaculture of lambari and Amazon river prawn (Macrobrachium amazonicum); and integrated aquaculture of lambari, Amazon river prawn, and curimbatá (Prochilodus lineatus). Fingerlings of lambari (0.8 ± 0.8 g) were stocked in twelve earthen-ponds (0.015 ha) at the density of 50 fish m⁻². Eight ponds were stocked with juveniles of Amazon river prawn (1.1 ± 0.2 g) at the density of 25 prawn m⁻². Four of these eight ponds were stocked with curimbatá fingerlings (0.2 ± 0.1 g) at a density of 13 fish m⁻². Only lambari was fed twice a day with an extruded commercial diet. The experiment lasted 60 days when lambari attained commercial size. The inclusion of prawn increased the total species yield from 1.8 to 2.4 t ha⁻¹ cycle⁻¹ and reduced the feed conversion ratio (FCR) from 2.5 to 1.8. The inclusion of prawn and curimbatá increased the total yield to 3.2 t ha⁻¹ cycle⁻¹ and reduced the FCR to 1.4. Therefore, the integrated culture of lambari, prawn, and curimbatá improves the use of space, water, feed, and benthic species to recover the large quantity of nutrients accumulated in the bottom of lambari pond production, converting them into high-nutritional and monetary-valued biomass.