Viability duration of pacu (Piaractus mesopotamicus) milt stored under refrigeration.

Cooling milt conserves viable spermatozoa to extend the period available for artificial fertilization and avoids the robust protocols and high costs associated with cryopreservation. Yet, the sperm quality curves of fresh and refrigerated milt have not yet been compared for pacu (Piaractus mesopotamicus), which is often used as a biological model. This study aimed to analyze the milt quality of male P. mesopotamicus across 24 h of refrigeration. Six adult males were induced with carp pituitary extract. Sperm movement, membrane integrity, and morphology was compared between extruded milt samples stored for 24 h under either ambient temperature or under refrigeration at 12.63 °C. Sperm motility differed significantly over time. After 24 h of storage, motility values were higher in refrigerated spermatozoa than in those kept at ambient temperature. Sperm cell survival rates did not differ 4-8 h post collection. After 16 h, refrigerated cells showed superior membrane integrity (82.05 ± 4.23%) compared to those stored at ambient temperature (66.98 ± 6.45%), maintaining this pattern up to 24 h. In terms of sperm morphology rate, milt from both treatment groups was still viable for use 8 h after collection. However, after 16 h of storage, both groups exhibited a large reduction in normality rates, and at 24 h, all milt were unfeasible. In conclusion, P. mesopotamicus milt can be stored up to 8 h after collection when refrigerated at 12.63 °C, without the use of extenders and/or cryoprotectants, maintaining enough quality for egg fertilization.

Growth and survival of Betta splendens fed microbial aggregates from ex-situ biofloc technology (BFT).

The betta (Betta splendens) is a carnivorous ornamental species that requires live food. In this study, we evaluated the growth and survival of Betta splendens fingerlings fed ex-situ biofloc (BFT). A total of 375 fingerlings (8.3 ± 4.1 mg and 0.8 ± 0.14 cm) were distributed into 15-L plastic tanks (n=25), with five replicates for each of the following treatments: (i) exclusive live food (LF100), (ii) exclusive biofloc (BFT100), (iii) live food supplemented with biofloc (LF100-BFT100), and a reduction of 15% (iv) and 30% (v) in live food with biofloc supplementation (LF85-BFT100 and LF70-BFT100, respectively). The fish were fed newly hatched brine shrimp (Artemia spp. nauplii) and/or fresh biofloc, twice daily, over a 16-day experimental period. Dietary supplementation of Beta splendens with ex-situ BFT (LF100-BFT100, LF85-BFT100, and LF70-BFT100) resulted in a similar final weight (P>0.05) compared to exclusive brine shrimp (LF100). Regarding total length, the fish in the LF100-BFT100 group were superior to those in the LF100 group (P<0.05). The LF100 and LF100-BFT100 groups showed survival rates of 100% and 98.4%, respectively, which were not statistically different (P>0.05). For all analyzed variables, fish exclusively fed biofloc (BFT100) exhibited unfavorable performance. These results indicate that dietary ex-situ biofloc supplementation, without reducing the supply of live food, can be an interesting alternative in the rearing of Betta splendens since biofloc improves growth performance and maintains a good survival rate.

Induced reproduction of yellow-tailed lambari (Astyanax lacustris) with Ovopel® and buserelin acetate as alternatives to the protocol with carp pituitary extract.

The objective of this study was to evaluate reproductive traits in adults of Astyanax lacustris subjected to different spawning inducers. The study involved 240 females (12.54 g ± 2.33 and 7.66 cm ± 0.63 cm) and 240 males (5.83 g ± 0.39 g and 6.14 cm ± 0.64 cm), all at reproductive age. Three different inducers were evaluated: (i) 0.4 pellets of Ovopel®/kg of body weight; (ii) 0.5 ml of buserelin acetate/kg of body weight; and (iii) carp pituitary extract (CPE) (5.5 mg CPE/kg body weight for females and 2.5 mg CPE/kg body weight for males), as well as saline solution (without hormone). The degree-hours for spawning were greater (P<0.05) for the Ovopel® treatment (with 204.93) than in the treatment with CPE (183.2). Ovary weight and gonadosomatic index were higher (P<0.05) in CPE and Ovopel® treatments when compared to buserelin acetate. The number of oocytes per female, absolute and relative fecundity were greater (P<0.05) for Ovopel® and CPE treatments. Fertilization rate was higher (P<0.05) in treatment with buserelin acetate (82.3%) in relation to Ovopel® (72.33%) and CPE (62.40%) treatments, and the highest (P<0.05) hatching rates were achieved with buserelin acetate and Ovopel®. The number of larvae per female body weight was greater (P<0.05) when Ovopel® was used. In conclusion, Ovopel® proves to be a more effective reproductive inducer for induced reproduction of A. lacustris when compared to CPE and buserelin acetate.