Environmental relevant concentrations of glyphosate-based herbicide as 50 µg l , 300 µg l and 1800 µg l can affect sperm quality of yellowtail tetra fish Astyanax lacustris. Viability of sperm cells was impaired at 300 µg l , a concentration that is within legal limits in U.S.A. waterbodies, while motility was impaired at 50 µg l , which is the more stringent limit set in Brazilian law. Therefore, environment protection agencies must review regulations of glyphosate-based herbicides on water bodies.

In this study, the aim was to establish a protocol for first feeding of diploid and triploid yellowtail tetra Astyanax altiparanae in laboratory conditions. The fry were fed with five different diets: (i) Artemia franciscana nauplii, (ii) plankton, (iii) dry food, (iv) Artemia franciscana nauplii + plankton, and (v) Artemia nauplii + plankton + dry food. Additionally, the growth and survival rates of diploid and triploid individuals were also evaluated. On day 10, the length of the fish between the treatments differed significantly (p = .0001) and ranged from 4.07 AE 0.06 mm (dry food) to 8.50 AE 0.64 mm (plankton + Artemia). The sizes of the fish increased with time, except for the fish fed with dry food. The survival rates were similar for the fish fed with the four diets and ranged from 80.7 AE 5.4% (dry food + plankton + Artemia to 92.0 AE 1.6% (plankton + Artemia), but differed from the fish fed with dry food (17.7 AE 5.8%, p = .0017). Diploids and triploids did not present differences on day 0 (p = .2252) and on day 10 (p = .4844) when the fish presented 6.77 AE 0.25 mm and 6.54 AE 0.15 mm respectively. Survival of diploids (87.3 AE 5.13%) and triploids (74.67 AE 2.30%) were also similar (p = .0285). These data are innovative and useful for establishing protocols for this species in both academic and applied sciences.

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Summary Triploidization plays an important role in aquaculture and surrogate technologies. In this study, we induced triploidy in the matrinxã fish (Brycon amazonicus) using a heat-shock technique. Embryos at 2 min post fertilization (mpf) were heat shocked at 38°C, 40°C, or 42°C for 2 min. Untreated, intact embryos were used as a control. Survival rates during early development were monitored and ploidy status was confirmed using flow cytometry and nuclear diameter analysis of erythrocytes. The hatching rate reduced with heat-shock treatment, and heat-shock treatments at 42°C resulted in no hatching events. Optimal results were obtained at 40°C with 95% of larvae exhibiting triploidy. Therefore, we report that heat-shock treatments of embryos (2 mpf) at 40°C for 2 min is an effective way to induce triploid individuals in B. amazonicus.