ORIGINAL ARTICLE /ARTÍCULO ORIGINAL

HELMINTH COMMUNITY STRUCTURE OF ARAPAIMA GIGAS IN SEMI-INTENSIVE

AND INTENSIVE FISH FARMING SYSTEMS IN THE SOUTHWESTERN BRAZILIAN

ESTRUCTURA DE LA COMUNIDAD DE HELMINTOS DE ARAPAIMA GIGAS EN

SISTEMAS SEMI-INTENSIVOS E INTENSIVOS DE CULTIVO EN EL SUROESTE DE

LA AMAZONIA BRASILEÑA

1,5 1 2,5

Maralina Torres da Silva ; Geazi Penha Pinto ; Pedro Hercílio de Oliveira Cavalcante ; Francisco Glauco de

Programa de Pós-Graduação em Biodiversidade e Saúde, Instituto Oswaldo Cruz, Fiocruz.

Corresponding author: Maralina Torres da Silva (Silva, MT),Instituto Federal do Acre – IFAC. Rua Rio Grande do Sul 2600,

Bairro Aeroporto Velho, Rio Branco, AC, Brazil, 69.911-030. Tel: +55 (68) 999844402. E-mail: maralina.silva@ifac.edu.br;

community structure of A. gigas comparing two farming systems. A total of 121 fish were

obtained from a semi-intensive and an intensive systems in the state of Acre, Brazil. A total of

nine species of parasites were identified, with only one species in common. There was a

significant difference with respect to parasite prevalence levels between the two fish farms (χ =

44.99 p < 0.05), and the fish from the semi-intensive system showed significantly higher levels of

infection (90.63%) than those from the intensive system (31.57%). In the semi-intensive system,

nine parasite species were collected and identified: Dawestrema cycloancistrium;

Capillostrongyloides arapaimae; Goezia spinulosa; Hysterothylacium sp.; Camallanidae gen.

sp.; Ascaridoidea gen. sp.; Polyacanthorhynchus sp. (juvenile), Neoechinorhynchus sp. and

enhance their production.

Palabras clave: Acanthocephala – acuicultura – Arapaima gigas – Brasil – Monogenea – Nematoda

En la Amazonia, las inversiones en nuevas tecnologías para el cultivo de peces se han hecho en

los últimos años. Arapaima gigas es considerada una de las especies con mayor potencial para la

piscicultura en la región. Los sistemas que cultivan esta especie en el Amazonas son muy

diversos, que van desde semi-intensivo para intensivo o industrial. El objetivo de este estudio fue

cultivo semi-intensivo mostraron niveles significativamente más altos de infección (90,63%)

que los del cultivo intensivo (31,57%). En el sistema semi-intensivo, se recolectaron e

identificaron nueve especies de parásitos: Dawestrema cycloancistrium; Capillostrongyloides

arapaimae; Goezia spinulosa; Hysterothylacium sp.; Camallanidae gen. sp.; Ascaridoidea gen.

sp.; Polyacanthorhynchus sp. (Juvenil), Neoechinorhynchus sp. y Acanthocephala gen. sp. En el

cultivo intensivo, sólo se encontró D. cycloancistrium, que representa el 100% de las muestras

recogidas. El análisis comparativo con respecto a la prevalencia de D. cycloancistrium entre los

dos cultivos de pescado mostró una diferencia significativa, con mayor prevalencia en el sistema

semi-intensivo (χ = 7,42 p = 0,006). Este es el primer estudio de la comunidad de parásitos de A.

of fish farming, due to the high diversity of fish

species, availability of water resources, stable

temperatures throughout the year, large areas

and strategic geographic position, enabling

connection with Asian and American markets

(Brown et al., 2002).

In recent years, the Amazon region has

received high investments to develop fish

farming. Several studies have been conducted

of fish species that have high market value and

greatest potential for fish farming in the region

(Roubach et al., 2003; Lima et al., 2015).

The arapaima farming systems in the Amazon

are highly diversified, ranging from semi-

intensive to intensive or industrial. Semi-

intensive breeding is usually performed by

family farmers, with little use of feeding,

moderate stocking densities and regular

renewal of water. The intensive system is

structured to provide a balanced diet, control

which fingerlings were grown after spawning.

In this environment, the supply of feed of crude

protein 40% was given twice a day. The stock

density was 0.15 fish/m .

In the intensive system, the breeding fish were

placed in earthen ponds where the water

supplied from local streams was renewed daily

and filtered in a system with 400 microns

mesh. The water temperature and oxygen were

tanks and then released into the growth ponds.

High quality balanced feed with 45% crude

protein was provided 6 to 8 times a day and

preventive control of parasites was carried out

with anthelmintics. During all phases, fry were

collected at random for analysis of possible

parasites in the farm's laboratory. The stock

density varied from 0.75 to 10 fish/m

depending on the size of the spawning from the

farm. The specimens were weighed (W),

measured for total length (TL) and examined in

saline medium and under a stereomicroscope.

The parasites were fixed in 70% ethanol and a

sample of each species was fixed in 4%

formalin for scanning electron microscopic

procedures (SEM). The formalin–fixed

specimens were washed in 0.1 M cacodylate

buffer pH 7.2, post-fixed in 1% OsO and 0.8%

Ludwig & Reynolds (1988) for each

infracommunity.

Dawestrema cycloancistrium

Goezia spinulosa

Hysterothylacium

Polyacanthorhynchus

Neoechinorhynchus

Dawestrema cycloancistrium

From the 64 specimens of A. gigas examined

from the semi-intensive fish farm, 58 (90.63%)

were parasitized by at least one species. A total

of 14,822 individual parasites were collected,

with mean of 255.55 parasites/fish. Six fish

hosts were not parasitized (9.38%); 22 fish

were infected by only one parasite species

(34.38%); 17 hosts harbored two parasite

species (26.56%); and 14 fish contained three

Table 2 Quantitative descriptors, infection/infestation site and community status of parasites of Arapaima gigas

from the two fish farms, Acre, Brazil

between total length of fish and parasite

abundance (Spearman rank correlation

coefficient, r= 0.54, p < 0.01).

At the intensive fish farm, 18 fish (31.57%)

with aluminum vats and circular concrete tanks where fingerlings are grown in the intensive fish farm.

Dawestrema cycloancistrium: total. 8. Hysterothylacium sp. (L3): total. 9. Hysterothylacium sp. (L3): anterior end provided with

ventral cephalic tooth, lateral view. 10. Polyacanthorhynchus sp. (juvenile): total.

One of the barriers to the production of the

arapaimas in fish farms is parasitic diseases,

which influence the quantity and quality of fish

produced (Gaines et al., 2012). Study of the

parasitic fish community structure provides a

range of information on habits and habitat of

The high prevalence of fish parasites in the

semi-intensive farm (90.63%) was similar to

that reported by Marinho et al. (2013) for the

same host species in fish farms in Amapá state

(northeastern Amazon region) and by Araújo et

al. (2009) in semi-intensive culture in

Amazonas state (central Amazon). This pattern

of infection, according to these authors, can be

associated with the inadequate tank

management. In the present study, this factor

level renewal with no filters, failure to control

oxygen and temperature parameters and lack

of disinfection of structures and devices can

facilitate the entrance and spread of parasites in

the system (Lima et al., 2015). In contrast, in

the intensive fish farming system, where the

water is renewed daily, filtered with a 400

mesh net, temperature and oxygen are

controlled daily and anthelmintics are used, the

parasitic infection was significantly lower,

with the water coming directly from nearby

(21.88%) were considered important, since C.

Polyacanthorhynchus have previously been

reported in arapaimas and have the ability to

penetrate the intestine wall for attachment,

parasites had an aggregated distribution

pattern. However, the Monogenea presented

particularly high values, indicating that in

farming systems where the density of hosts is

high, these parasites with direct life cycle have

greater dispersion capacity.