Arapaima gigas (paiche) is the largest scaled fish species living in the Amazon basin. Its biology is both fascinating and misunderstood. In a context of overfishing, hence reduced natural populations, aquaculture of a fish with such interesting characteristics (large size, high growth rate, no intramuscular spines) is an important issue. The development of farming production would also reduce the fishing pressure on natural populations and allow re‐stocking programmes in certain areas. To determine what factors may influence the reproductive success in captivity, data from breeding reports for 2007–2010 were collected among fish farmers in the region of Iquitos. In parallel, we carried out physicochemical measurements in different ponds where these paiches breed, and conducted personal interviews about the general fish management conditions. The results show that reproduction occurs throughout the year but with a higher intensity during the rainy season. It also highlights farms that have performed much better than others, but no single factor except feeding level has been clearly associated with reproductive success. The environmental control of reproduction in paiche, therefore, remains partly mysterious. To deepen this study, we recommend the systematic sexing of breeders, extending reproductive behavioural studies, and examining the limnological factors involved in fry mortality.

Meal frequency is a key parameter in fish larviculture, especially in highly cannibalistic species. Knowledge of the biological bases of cannibalism (growth capacity of cannibals, morphological constraints on cannibalism, prey size preference) can help predicting the risks of cannibalism for different feeding schedules under culture conditions. This study relied on the day-by-day analysis of prey size preference and bioenergetics of individual cannibals of the catfish Pseudoplatystoma punctifer (8–65 mm standard length, SL, 0.5–400 mg dry mass, DM) at 28.5 °C under 12L:12D. The results were equated with the ontogenetic variations of morphological factors (head and mouth width) and feed efficiency of larvae feeding on Artemia nauplii, in order to calculate the risks of cannibalism among fish fed 2–7 daily meals. The predation capacities of P. punctifer were highest at 8 mm SL and decreased in larger fish (largest prey = 86% and 70% SL in fish of 8 and >30 mm SL, respectively). Cannibals of increasing size preferred increasingly smaller prey relative to their own size, but also to their predation capacities. These morphological and behavioural constraints were largely compensated for by bioenergetics performance. Cannibals consumed high daily food rations (as high as 171 and 29% DM in fish 300 mg DM, respectively), exhibited high gross conversion efficiencies (0.50–0.55 and about 0.70, in fish 30 mg DM, respectively), and grew rapidly (90 and 18% DM day-1 in fish 300 mg DM, respectively). The growth advantage of cannibals over siblings fed Artemia nauplii was decisive, except for high meal frequencies (6–7 daily meals). This study supports the view that the risk of cannibalism and adequate feeding strategies can be largely predicted in a particular fish species if the morphological, behavioural and bioenergetics bases of cannibalism are examined altogether in an ontogenetic perspective.

Tara production occurs mainly in the altitude gradient, where the edaphoclimatic conditions that affect the production of pods still need to be understood. The goal was to determine the altitudinal and edaphoclimatic effect on the production of tara pods in agroforestry and natural remnants in Cajamarca, Peru. Data analyses performed were the following: principal component analysis (PCA), regression analysis, the bootstrap method, and Pearson correlation analysis. For each 1 °C increase in temperature, the length and width of the pod decreased by 2.1 and 0.62 mm, and of the seed by 0.17 and 0.12 mm in the agroforestry environment; likewise, pod, valve, seed and gum weights were reduced by 23.9, 10.9, 13 and 2.3 g in the agroforestry environment, and 22.3, 13, 9.3 and 2.1 g in the natural environment. Activities such as association with annual crops and perennial pasture possibly favor the length and width of the pod and seed and the weight of the pod, valve, seed and gum in the agroforestry environment when compared to the natural environment. Larger pod and seed dimensions and higher pod, valve, seed and gum weights are related to higher soil CaCO₃ contents in the natural environment and higher soil P and B contents in the agroforestry environment at higher altitudes. Higher Fe contents in the soil suggest an improvement in tara’s tannin weight (valve) in the natural and agroforestry environment. The effective response of tara, reflected in its weight and size of pods, was higher in an agroforestry environment than in a natural environment. Further studies on the production of tara pods are necessary for a better understanding of the interaction between altitude and soil fertility to expand the revenue and employment of Peruvian tara farmers.