This study aims to evaluate the effect of different initial densities of Nile tilapia fingerlings on water quality, fish growth, and production of marjoram (Origanum majorana L.) and sweet basil (Ocimum basilicum L.) in a recirculating aquaponic set up. The experiment was carried out on randomized block design and comprised four fish densities (0, 150, 250 and 500 fish m-3) and two crops, in which each treatment was continued for 45 days and replicated three times. Except for pH and total alkalinity, all water physicochemical parameters were increased significantly at high fish densities. In contrast, most of the biological parameters for fish were unaffected by culture density, although at the highest density crude protein percentage was significantly increased and ether extract percentage was significantly reduced. Plant productivities were highest when fish were cultured at density of 500 fish m-3 , a density that was found to be appropriate for maintaining water quality and promoting fish growth while preventing toxicity and mortality. The present study has demonstrated the technical viability of coupling Nile tilapia culture coup with aquaponic production of marjoram and sweet basil.

This study aims to evaluate a particular property in Brasília that uses the aquaponics system on a small production scale. The Monte Carlo method was used to estimate its financial feasibility and the probability of the production volume and, consequently, evaluate the risk of this undertaking. The data analyzed included fixed and variable costs, revenues and financial viability indicators, which are net present value (NPV), periodic economic benefit (PEB) and internal rate of return (IRR). It was identified in this research that the cost with the largest participation was the land acquisition, amounting to more than 60%. According to the survey, the venture showed a 56.69% probability to generate a NPV, PEB and IRR rate, respectively, of R$ 117,784.26, R$ 16,003.11 and 37%. The probability of occurrence of fish volume and plant production were, respectively, 1179.44 kg and 731.26 kg with 74.43% and 76.16%, presenting a probability greater than 50%, which is considered as more reliable than traditional analysis. Therefore, we can conclude that it is economically viable according to the NPV parameters, which was greater than zero, and the IRR, that was higher than the minimum rate of attractiveness.

-The objective of this work was to evaluate the effect of photoperiod on luteinizing hormone (LH) plasma levels and gonadal maturation of lambari females. One hundred and twenty adult lambaris, distributed into 12 aquaria of 20 L each, were randomly subjected to three different treatments, in a completely randomized design, and four replicates. Treatments were photoperiods in hours of light (L) and darkness (D): T1, 0 L:24 D; T2, 12 L:12 D; T3, 24 L:0 D. After 40 days, fish were subjected to fasting for 24 hours and, then, anesthetized. Immediately after slaughter, fish were weighed, and their gonads and livers were removed and weighed. Ovaries were weighed and immersed in Bouin's fixative solution for 24 hours and, then, kept in 70% alcohol until processing the material. Subsequently, the oocyte developmental stage was determined. No significant differences were observed between treatments for final weight, ovary weight, gonadosomatic index (GSI), hepatosomatic index (HSI) and LH levels. In all treatments, lambari females showed maturing ovaries with prevalence of vitellogenic oocytes. Photoperiod does not affect the LH levels and ovarian maturation in lambari females.Index terms: Astyanax bimaculatus, native species, gonadosomatic index, hepatosomatic index, oogenesis. Níveis plasmáticos de hormônio luteinizante e maturação gonadal de fêmeas de lambari sob diferentes fotoperíodos