Frozen zooplankton is efficient as natural food during pirarucu Arapaima gigas weaning

Abstract

The commercial production of carnivorous fish depends on the feed training that can be made through the direct transition from natural food to inert food. As using live natural food requires care in production, alternative methods of using live food are necessary, such as freezing. Thus, the aim of this study was to evaluate the use of frozen zooplankton as an initial diet in the feed training of pirarucu Arapaima gigas juveniles. Three hundred and twenty pirarucu juveniles (13.94 ± 4.99 g) were submitted to weaning with two different initial diets (treatments): live zooplankton and frozen zooplankton. The co‐feeding period was 12 days, with a progressive increase in the amount of feed offered and a decrease in zooplankton every three days. At the end of the training, all fish were ready to be fed with commercial feed. There was no mortality in the experiment and no significant differences (p > 0.05) for weight, length, weight variation coefficient, specific growth rate, intestinal coefficient, hepatosomatic index, muscle layer thickness and height of the branched folds intestinal mucosa, moisture, crude protein and carcass energy for fish that received live or frozen zooplankton as a starter. Isotopic values of δ15 N and δ13C in the fish's muscle were similar (p > 0.05), reinforcing no feeding preference of the fish between the live or frozen zooplankton. The water quality was not influenced by the use of initial diet (p > 0.05). The frozen zooplankton can be used as initial food for pirarucu juveniles feed training, without impairing fish growth and survival.

Parasitism of Arapaima gigas (Schinz, 1822) in fish farms of the state of Amazonas, Brazil

“…The supply of live zooplankton collected in the cultivation facilities for food training can be a source of parasite contamination for juvenile A. gigas (Lima et al, 2017;Fonseca & Pereira, 2021). However, the use of previously frozen zooplankton does not impair the growth and survival of juvenile A. gigas, and this may be a strategy to minimize the transmission of parasites by oral route in the feeding training phase (Lima et al, 2021). In addition, the inclusion of immunostimulating additives (Aquate Fish ™, 12 g kg -1 diet) that promote the improvement in the immunity of juvenile A. gigas may be an alternative to increase the defenses of fish against pathogens (Dias et al, 2019).…”

“…One species of native fish with great potential for aquaculture is Arapaima gigas Schinz, 1822, since it has as remarkable biological aspects such as its rapid growth and air breathing. It also has characteristics that are conducive to breeding such as the possibility of carrying out the feeding transition from live food to commercial feed and the ability to withstand high storage densities in nurseries and during growout phase (Oliveira et al, 2020;Pereira-Filho et al, 2020;Santana et al, 2020;Lima et al, 2021). The state of Amazonas has a number of large-scale fish producing centers.…”

Sodium chloride against Dawestrema cycloancistrium in juvenile Arapaima gigas

“…The occurrence of monogenoids in pirarucu is a limiting factor for its rearing in production systems, with the predominance of two species, Dawestrema cycloancistrium and Dawestrema cycloancistrioides, affecting pirarucu juveniles from the rst days of life (Araújo et Parasitic infestations in sh farming activities can be avoided by adopting Good Management Practices (GMP's) (Corral et al 2018;Silva et al 2019) and nutritional adjustments (Lima et al 2021). Furthermore, the use of prophylaxis and disease treatment diseases products, as well as immunostimulants, is also recommended.…”